diff --git a/Action.h b/Action.h
index 1dfdcb47..a2920b68 100644
--- a/Action.h
+++ b/Action.h
@@ -39,20 +39,20 @@ typedef struct State_ {
 } State;
 
 
-Object* Action_pickFromVector(State* st, Panel* list, int x);
+extern Object* Action_pickFromVector(State* st, Panel* list, int x);
 
 // ----------------------------------------
 
-bool Action_setUserOnly(const char* userName, uid_t* userId);
+extern bool Action_setUserOnly(const char* userName, uid_t* userId);
 
-Htop_Reaction Action_setSortKey(Settings* settings, ProcessField sortKey);
+extern Htop_Reaction Action_setSortKey(Settings* settings, ProcessField sortKey);
 
 // ----------------------------------------
 
-Htop_Reaction Action_follow(State* st);
+extern Htop_Reaction Action_follow(State* st);
 
 
-void Action_setBindings(Htop_Action* keys);
+extern void Action_setBindings(Htop_Action* keys);
 
 
 #endif
diff --git a/Affinity.h b/Affinity.h
index fd2c599e..818b905e 100644
--- a/Affinity.h
+++ b/Affinity.h
@@ -29,23 +29,23 @@ typedef struct Affinity_ {
 } Affinity;
 
 
-Affinity* Affinity_new(ProcessList* pl);
+extern Affinity* Affinity_new(ProcessList* pl);
 
-void Affinity_delete(Affinity* this);
+extern void Affinity_delete(Affinity* this);
 
-void Affinity_add(Affinity* this, int id);
+extern void Affinity_add(Affinity* this, int id);
 
 #ifdef HAVE_LIBHWLOC
 
-Affinity* Affinity_get(Process* proc, ProcessList* pl);
+extern Affinity* Affinity_get(Process* proc, ProcessList* pl);
 
-bool Affinity_set(Process* proc, Affinity* this);
+extern bool Affinity_set(Process* proc, Affinity* this);
 
 #elif HAVE_LINUX_AFFINITY
 
-Affinity* Affinity_get(Process* proc, ProcessList* pl);
+extern Affinity* Affinity_get(Process* proc, ProcessList* pl);
 
-bool Affinity_set(Process* proc, Affinity* this);
+extern bool Affinity_set(Process* proc, Affinity* this);
 
 #endif
 
diff --git a/AffinityPanel.h b/AffinityPanel.h
index 2b6059b0..3a9c7807 100644
--- a/AffinityPanel.h
+++ b/AffinityPanel.h
@@ -16,8 +16,8 @@ in the source distribution for its full text.
 
 extern PanelClass AffinityPanel_class;
 
-Panel* AffinityPanel_new(ProcessList* pl, Affinity* affinity);
+extern Panel* AffinityPanel_new(ProcessList* pl, Affinity* affinity);
 
-Affinity* AffinityPanel_getAffinity(Panel* this, ProcessList* pl);
+extern Affinity* AffinityPanel_getAffinity(Panel* this, ProcessList* pl);
 
 #endif
diff --git a/AvailableColumnsPanel.h b/AvailableColumnsPanel.h
index 5a8371dd..2d6daf4b 100644
--- a/AvailableColumnsPanel.h
+++ b/AvailableColumnsPanel.h
@@ -19,6 +19,6 @@ typedef struct AvailableColumnsPanel_ {
 
 extern PanelClass AvailableColumnsPanel_class;
 
-AvailableColumnsPanel* AvailableColumnsPanel_new(Panel* columns);
+extern AvailableColumnsPanel* AvailableColumnsPanel_new(Panel* columns);
 
 #endif
diff --git a/AvailableMetersPanel.h b/AvailableMetersPanel.h
index e9b949b0..00e0f596 100644
--- a/AvailableMetersPanel.h
+++ b/AvailableMetersPanel.h
@@ -27,6 +27,6 @@ typedef struct AvailableMetersPanel_ {
 
 extern PanelClass AvailableMetersPanel_class;
 
-AvailableMetersPanel* AvailableMetersPanel_new(Settings* settings, Header* header, Panel* leftMeters, Panel* rightMeters, ScreenManager* scr, ProcessList* pl);
+extern AvailableMetersPanel* AvailableMetersPanel_new(Settings* settings, Header* header, Panel* leftMeters, Panel* rightMeters, ScreenManager* scr, ProcessList* pl);
 
 #endif
diff --git a/CategoriesPanel.h b/CategoriesPanel.h
index ccef0fae..44c6842a 100644
--- a/CategoriesPanel.h
+++ b/CategoriesPanel.h
@@ -24,10 +24,10 @@ typedef struct CategoriesPanel_ {
 } CategoriesPanel;
 
 
-void CategoriesPanel_makeMetersPage(CategoriesPanel* this);
+extern void CategoriesPanel_makeMetersPage(CategoriesPanel* this);
 
 extern PanelClass CategoriesPanel_class;
 
-CategoriesPanel* CategoriesPanel_new(ScreenManager* scr, Settings* settings, Header* header, ProcessList* pl);
+extern CategoriesPanel* CategoriesPanel_new(ScreenManager* scr, Settings* settings, Header* header, ProcessList* pl);
 
 #endif
diff --git a/CheckItem.h b/CheckItem.h
index 5847d4b2..dbd1a039 100644
--- a/CheckItem.h
+++ b/CheckItem.h
@@ -21,12 +21,12 @@ typedef struct CheckItem_ {
 
 extern ObjectClass CheckItem_class;
 
-CheckItem* CheckItem_newByRef(char* text, bool* ref);
+extern CheckItem* CheckItem_newByRef(char* text, bool* ref);
 
-CheckItem* CheckItem_newByVal(char* text, bool value);
+extern CheckItem* CheckItem_newByVal(char* text, bool value);
 
-void CheckItem_set(CheckItem* this, bool value);
+extern void CheckItem_set(CheckItem* this, bool value);
 
-bool CheckItem_get(CheckItem* this);
+extern bool CheckItem_get(CheckItem* this);
 
 #endif
diff --git a/ColorsPanel.h b/ColorsPanel.h
index ee3111e0..82b782b8 100644
--- a/ColorsPanel.h
+++ b/ColorsPanel.h
@@ -29,6 +29,6 @@ typedef struct ColorsPanel_ {
 
 extern PanelClass ColorsPanel_class;
 
-ColorsPanel* ColorsPanel_new(Settings* settings, ScreenManager* scr);
+extern ColorsPanel* ColorsPanel_new(Settings* settings, ScreenManager* scr);
 
 #endif
diff --git a/ColumnsPanel.h b/ColumnsPanel.h
index 0da674a8..46d20bbb 100644
--- a/ColumnsPanel.h
+++ b/ColumnsPanel.h
@@ -22,11 +22,11 @@ typedef struct ColumnsPanel_ {
 
 extern PanelClass ColumnsPanel_class;
 
-ColumnsPanel* ColumnsPanel_new(Settings* settings);
+extern ColumnsPanel* ColumnsPanel_new(Settings* settings);
 
-int ColumnsPanel_fieldNameToIndex(const char* name);
+extern int ColumnsPanel_fieldNameToIndex(const char* name);
 
-void ColumnsPanel_update(Panel* super);
+extern void ColumnsPanel_update(Panel* super);
 
 
 #endif
diff --git a/DisplayOptionsPanel.h b/DisplayOptionsPanel.h
index 2a7509ae..d9de4005 100644
--- a/DisplayOptionsPanel.h
+++ b/DisplayOptionsPanel.h
@@ -23,6 +23,6 @@ typedef struct DisplayOptionsPanel_ {
 
 extern PanelClass DisplayOptionsPanel_class;
 
-DisplayOptionsPanel* DisplayOptionsPanel_new(Settings* settings, ScreenManager* scr);
+extern DisplayOptionsPanel* DisplayOptionsPanel_new(Settings* settings, ScreenManager* scr);
 
 #endif
diff --git a/EnvScreen.h b/EnvScreen.h
index 7cdbb865..025cb8d3 100644
--- a/EnvScreen.h
+++ b/EnvScreen.h
@@ -11,12 +11,12 @@ typedef struct EnvScreen_ {
 
 extern InfoScreenClass EnvScreen_class;
 
-EnvScreen* EnvScreen_new(Process* process);
+extern EnvScreen* EnvScreen_new(Process* process);
 
-void EnvScreen_delete(Object* this);
+extern void EnvScreen_delete(Object* this);
 
-void EnvScreen_draw(InfoScreen* this);
+extern void EnvScreen_draw(InfoScreen* this);
 
-void EnvScreen_scan(InfoScreen* this);
+extern void EnvScreen_scan(InfoScreen* this);
 
 #endif
diff --git a/FunctionBar.h b/FunctionBar.h
index b60f6582..ee5b9347 100644
--- a/FunctionBar.h
+++ b/FunctionBar.h
@@ -22,18 +22,18 @@ typedef struct FunctionBar_ {
 
 
 
-FunctionBar* FunctionBar_newEnterEsc(const char* enter, const char* esc);
+extern FunctionBar* FunctionBar_newEnterEsc(const char* enter, const char* esc);
 
-FunctionBar* FunctionBar_new(const char* const* functions, const char* const* keys, const int* events);
+extern FunctionBar* FunctionBar_new(const char* const* functions, const char* const* keys, const int* events);
 
-void FunctionBar_delete(FunctionBar* this);
+extern void FunctionBar_delete(FunctionBar* this);
 
-void FunctionBar_setLabel(FunctionBar* this, int event, const char* text);
+extern void FunctionBar_setLabel(FunctionBar* this, int event, const char* text);
 
-void FunctionBar_draw(const FunctionBar* this, char* buffer);
+extern void FunctionBar_draw(const FunctionBar* this, char* buffer);
 
-void FunctionBar_drawAttr(const FunctionBar* this, char* buffer, int attr);
+extern void FunctionBar_drawAttr(const FunctionBar* this, char* buffer, int attr);
 
-int FunctionBar_synthesizeEvent(const FunctionBar* this, int pos);
+extern int FunctionBar_synthesizeEvent(const FunctionBar* this, int pos);
 
 #endif
diff --git a/Hashtable.h b/Hashtable.h
index 25608961..32b02188 100644
--- a/Hashtable.h
+++ b/Hashtable.h
@@ -30,20 +30,20 @@ struct Hashtable_ {
 
 #ifdef DEBUG
 
-int Hashtable_count(Hashtable* this);
+extern int Hashtable_count(Hashtable* this);
 
 #endif
 
-Hashtable* Hashtable_new(int size, bool owner);
+extern Hashtable* Hashtable_new(int size, bool owner);
 
-void Hashtable_delete(Hashtable* this);
+extern void Hashtable_delete(Hashtable* this);
 
-void Hashtable_put(Hashtable* this, unsigned int key, void* value);
+extern void Hashtable_put(Hashtable* this, unsigned int key, void* value);
 
-void* Hashtable_remove(Hashtable* this, unsigned int key);
+extern void* Hashtable_remove(Hashtable* this, unsigned int key);
 
 extern void* Hashtable_get(Hashtable* this, unsigned int key);
 
-void Hashtable_foreach(Hashtable* this, Hashtable_PairFunction f, void* userData);
+extern void Hashtable_foreach(Hashtable* this, Hashtable_PairFunction f, void* userData);
 
 #endif
diff --git a/Header.h b/Header.h
index 700ad354..f5182454 100644
--- a/Header.h
+++ b/Header.h
@@ -31,30 +31,30 @@ typedef struct Header_ {
 #define Header_forEachColumn(this_, i_) for (int (i_)=0; (i_) < (this_)->nrColumns; ++(i_))
 #endif
 
-Header* Header_new(struct ProcessList_* pl, Settings* settings, int nrColumns);
+extern Header* Header_new(struct ProcessList_* pl, Settings* settings, int nrColumns);
 
-void Header_delete(Header* this);
+extern void Header_delete(Header* this);
 
-void Header_populateFromSettings(Header* this);
+extern void Header_populateFromSettings(Header* this);
 
-void Header_writeBackToSettings(const Header* this);
+extern void Header_writeBackToSettings(const Header* this);
 
-MeterModeId Header_addMeterByName(Header* this, char* name, int column);
+extern MeterModeId Header_addMeterByName(Header* this, char* name, int column);
 
-void Header_setMode(Header* this, int i, MeterModeId mode, int column);
+extern void Header_setMode(Header* this, int i, MeterModeId mode, int column);
 
-Meter* Header_addMeterByClass(Header* this, MeterClass* type, int param, int column);
+extern Meter* Header_addMeterByClass(Header* this, MeterClass* type, int param, int column);
 
-int Header_size(Header* this, int column);
+extern int Header_size(Header* this, int column);
 
-char* Header_readMeterName(Header* this, int i, int column);
+extern char* Header_readMeterName(Header* this, int i, int column);
 
-MeterModeId Header_readMeterMode(Header* this, int i, int column);
+extern MeterModeId Header_readMeterMode(Header* this, int i, int column);
 
-void Header_reinit(Header* this);
+extern void Header_reinit(Header* this);
 
-void Header_draw(const Header* this);
+extern void Header_draw(const Header* this);
 
-int Header_calculateHeight(Header* this);
+extern int Header_calculateHeight(Header* this);
 
 #endif
diff --git a/IncSet.h b/IncSet.h
index 27538f4b..d873bb81 100644
--- a/IncSet.h
+++ b/IncSet.h
@@ -41,18 +41,18 @@ typedef struct IncSet_ {
 typedef const char* (*IncMode_GetPanelValue)(Panel*, int);
 
 
-IncSet* IncSet_new(FunctionBar* bar);
+extern IncSet* IncSet_new(FunctionBar* bar);
 
-void IncSet_delete(IncSet* this);
+extern void IncSet_delete(IncSet* this);
 
-bool IncSet_handleKey(IncSet* this, int ch, Panel* panel, IncMode_GetPanelValue getPanelValue, Vector* lines);
+extern bool IncSet_handleKey(IncSet* this, int ch, Panel* panel, IncMode_GetPanelValue getPanelValue, Vector* lines);
 
-const char* IncSet_getListItemValue(Panel* panel, int i);
+extern const char* IncSet_getListItemValue(Panel* panel, int i);
 
-void IncSet_activate(IncSet* this, IncType type, Panel* panel);
+extern void IncSet_activate(IncSet* this, IncType type, Panel* panel);
 
-void IncSet_drawBar(IncSet* this);
+extern void IncSet_drawBar(IncSet* this);
 
-int IncSet_synthesizeEvent(IncSet* this, int x);
+extern int IncSet_synthesizeEvent(IncSet* this, int x);
 
 #endif
diff --git a/InfoScreen.h b/InfoScreen.h
index 2e1599f9..b9387cda 100644
--- a/InfoScreen.h
+++ b/InfoScreen.h
@@ -38,16 +38,16 @@ struct InfoScreen_ {
    Vector* lines;
 };
 
-InfoScreen* InfoScreen_init(InfoScreen* this, Process* process, FunctionBar* bar, int height, char* panelHeader);
+extern InfoScreen* InfoScreen_init(InfoScreen* this, Process* process, FunctionBar* bar, int height, char* panelHeader);
 
-InfoScreen* InfoScreen_done(InfoScreen* this);
+extern InfoScreen* InfoScreen_done(InfoScreen* this);
 
-void InfoScreen_drawTitled(InfoScreen* this, char* fmt, ...);
+extern void InfoScreen_drawTitled(InfoScreen* this, char* fmt, ...);
 
-void InfoScreen_addLine(InfoScreen* this, const char* line);
+extern void InfoScreen_addLine(InfoScreen* this, const char* line);
 
-void InfoScreen_appendLine(InfoScreen* this, const char* line);
+extern void InfoScreen_appendLine(InfoScreen* this, const char* line);
 
-void InfoScreen_run(InfoScreen* this);
+extern void InfoScreen_run(InfoScreen* this);
 
 #endif
diff --git a/ListItem.h b/ListItem.h
index b48f0acd..7fed9237 100644
--- a/ListItem.h
+++ b/ListItem.h
@@ -21,13 +21,13 @@ typedef struct ListItem_ {
 
 extern ObjectClass ListItem_class;
 
-ListItem* ListItem_new(const char* value, int key);
+extern ListItem* ListItem_new(const char* value, int key);
 
-void ListItem_append(ListItem* this, const char* text);
+extern void ListItem_append(ListItem* this, const char* text);
 
-const char* ListItem_getRef(ListItem* this);
+extern const char* ListItem_getRef(ListItem* this);
 
-long ListItem_compare(const void* cast1, const void* cast2);
+extern long ListItem_compare(const void* cast1, const void* cast2);
 
 
 #endif
diff --git a/MainPanel.h b/MainPanel.h
index 88496597..8d753306 100644
--- a/MainPanel.h
+++ b/MainPanel.h
@@ -31,22 +31,22 @@ typedef bool(*MainPanel_ForeachProcessFn)(Process*, Arg);
 #define MainPanel_getFunctionBar(this_) (((Panel*)(this_))->defaultBar)
 
 
-void MainPanel_updateTreeFunctions(MainPanel* this, bool mode);
+extern void MainPanel_updateTreeFunctions(MainPanel* this, bool mode);
 
-void MainPanel_pidSearch(MainPanel* this, int ch);
+extern void MainPanel_pidSearch(MainPanel* this, int ch);
 
-int MainPanel_selectedPid(MainPanel* this);
+extern int MainPanel_selectedPid(MainPanel* this);
 
-const char* MainPanel_getValue(MainPanel* this, int i);
+extern const char* MainPanel_getValue(MainPanel* this, int i);
 
-bool MainPanel_foreachProcess(MainPanel* this, MainPanel_ForeachProcessFn fn, Arg arg, bool* wasAnyTagged);
+extern bool MainPanel_foreachProcess(MainPanel* this, MainPanel_ForeachProcessFn fn, Arg arg, bool* wasAnyTagged);
 
 extern PanelClass MainPanel_class;
 
-MainPanel* MainPanel_new();
+extern MainPanel* MainPanel_new();
 
-void MainPanel_setState(MainPanel* this, State* state);
+extern void MainPanel_setState(MainPanel* this, State* state);
 
-void MainPanel_delete(Object* object);
+extern void MainPanel_delete(Object* object);
 
 #endif
diff --git a/Meter.h b/Meter.h
index d98c910e..36e0e815 100644
--- a/Meter.h
+++ b/Meter.h
@@ -109,17 +109,17 @@ typedef struct GraphData_ {
 
 extern MeterClass Meter_class;
 
-Meter* Meter_new(struct ProcessList_* pl, int param, MeterClass* type);
+extern Meter* Meter_new(struct ProcessList_* pl, int param, MeterClass* type);
 
-int Meter_humanUnit(char* buffer, unsigned long int value, int size);
+extern int Meter_humanUnit(char* buffer, unsigned long int value, int size);
 
-void Meter_delete(Object* cast);
+extern void Meter_delete(Object* cast);
 
-void Meter_setCaption(Meter* this, const char* caption);
+extern void Meter_setCaption(Meter* this, const char* caption);
 
-void Meter_setMode(Meter* this, int modeIndex);
+extern void Meter_setMode(Meter* this, int modeIndex);
 
-ListItem* Meter_toListItem(Meter* this, bool moving);
+extern ListItem* Meter_toListItem(Meter* this, bool moving);
 
 /* ---------- TextMeterMode ---------- */
 
diff --git a/MetersPanel.h b/MetersPanel.h
index e00169c8..12eabbe6 100644
--- a/MetersPanel.h
+++ b/MetersPanel.h
@@ -34,10 +34,10 @@ struct MetersPanel_ {
 // In <http://unicode.org/reports/tr11/>, arrows (U+2019..U+2199) are
 // considered "Ambiguous characters".
 
-void MetersPanel_setMoving(MetersPanel* this, bool moving);
+extern void MetersPanel_setMoving(MetersPanel* this, bool moving);
 
 extern PanelClass MetersPanel_class;
 
-MetersPanel* MetersPanel_new(Settings* settings, const char* header, Vector* meters, ScreenManager* scr);
+extern MetersPanel* MetersPanel_new(Settings* settings, const char* header, Vector* meters, ScreenManager* scr);
 
 #endif
diff --git a/Object.h b/Object.h
index 19a667c8..bcf2c481 100644
--- a/Object.h
+++ b/Object.h
@@ -46,7 +46,7 @@ extern ObjectClass Object_class;
 
 #ifdef DEBUG
 
-bool Object_isA(Object* o, const ObjectClass* klass);
+extern bool Object_isA(Object* o, const ObjectClass* klass);
 
 #endif
 
diff --git a/OpenFilesScreen.h b/OpenFilesScreen.h
index 8160cfe2..39c71d5b 100644
--- a/OpenFilesScreen.h
+++ b/OpenFilesScreen.h
@@ -34,12 +34,12 @@ typedef struct OpenFilesScreen_ {
 
 extern InfoScreenClass OpenFilesScreen_class;
 
-OpenFilesScreen* OpenFilesScreen_new(Process* process);
+extern OpenFilesScreen* OpenFilesScreen_new(Process* process);
 
-void OpenFilesScreen_delete(Object* this);
+extern void OpenFilesScreen_delete(Object* this);
 
-void OpenFilesScreen_draw(InfoScreen* this);
+extern void OpenFilesScreen_draw(InfoScreen* this);
 
-void OpenFilesScreen_scan(InfoScreen* this);
+extern void OpenFilesScreen_scan(InfoScreen* this);
 
 #endif
diff --git a/Panel.h b/Panel.h
index 5253fc2e..b7480c6b 100644
--- a/Panel.h
+++ b/Panel.h
@@ -75,52 +75,52 @@ struct Panel_ {
 
 extern PanelClass Panel_class;
 
-Panel* Panel_new(int x, int y, int w, int h, bool owner, ObjectClass* type, FunctionBar* fuBar);
+extern Panel* Panel_new(int x, int y, int w, int h, bool owner, ObjectClass* type, FunctionBar* fuBar);
 
-void Panel_delete(Object* cast);
+extern void Panel_delete(Object* cast);
 
-void Panel_init(Panel* this, int x, int y, int w, int h, ObjectClass* type, bool owner, FunctionBar* fuBar);
+extern void Panel_init(Panel* this, int x, int y, int w, int h, ObjectClass* type, bool owner, FunctionBar* fuBar);
 
-void Panel_done(Panel* this);
+extern void Panel_done(Panel* this);
 
-void Panel_setSelectionColor(Panel* this, int color);
+extern void Panel_setSelectionColor(Panel* this, int color);
 
-RichString* Panel_getHeader(Panel* this);
+extern RichString* Panel_getHeader(Panel* this);
 
 extern void Panel_setHeader(Panel* this, const char* header);
 
-void Panel_move(Panel* this, int x, int y);
+extern void Panel_move(Panel* this, int x, int y);
 
-void Panel_resize(Panel* this, int w, int h);
+extern void Panel_resize(Panel* this, int w, int h);
 
-void Panel_prune(Panel* this);
+extern void Panel_prune(Panel* this);
 
-void Panel_add(Panel* this, Object* o);
+extern void Panel_add(Panel* this, Object* o);
 
-void Panel_insert(Panel* this, int i, Object* o);
+extern void Panel_insert(Panel* this, int i, Object* o);
 
-void Panel_set(Panel* this, int i, Object* o);
+extern void Panel_set(Panel* this, int i, Object* o);
 
-Object* Panel_get(Panel* this, int i);
+extern Object* Panel_get(Panel* this, int i);
 
-Object* Panel_remove(Panel* this, int i);
+extern Object* Panel_remove(Panel* this, int i);
 
-Object* Panel_getSelected(Panel* this);
+extern Object* Panel_getSelected(Panel* this);
 
-void Panel_moveSelectedUp(Panel* this);
+extern void Panel_moveSelectedUp(Panel* this);
 
-void Panel_moveSelectedDown(Panel* this);
+extern void Panel_moveSelectedDown(Panel* this);
 
-int Panel_getSelectedIndex(Panel* this);
+extern int Panel_getSelectedIndex(Panel* this);
 
-int Panel_size(Panel* this);
+extern int Panel_size(Panel* this);
 
-void Panel_setSelected(Panel* this, int selected);
+extern void Panel_setSelected(Panel* this, int selected);
 
-void Panel_draw(Panel* this, bool focus);
+extern void Panel_draw(Panel* this, bool focus);
 
-bool Panel_onKey(Panel* this, int key);
+extern bool Panel_onKey(Panel* this, int key);
 
-HandlerResult Panel_selectByTyping(Panel* this, int ch);
+extern HandlerResult Panel_selectByTyping(Panel* this, int ch);
 
 #endif
diff --git a/Process.h b/Process.h
index f702ca00..7ecd81c5 100644
--- a/Process.h
+++ b/Process.h
@@ -173,36 +173,36 @@ typedef struct ProcessClass_ {
 
 extern char Process_pidFormat[20];
 
-void Process_setupColumnWidths();
+extern void Process_setupColumnWidths();
 
-void Process_humanNumber(RichString* str, unsigned long number, bool coloring);
+extern void Process_humanNumber(RichString* str, unsigned long number, bool coloring);
 
-void Process_colorNumber(RichString* str, unsigned long long number, bool coloring);
+extern void Process_colorNumber(RichString* str, unsigned long long number, bool coloring);
 
-void Process_printTime(RichString* str, unsigned long long totalHundredths);
+extern void Process_printTime(RichString* str, unsigned long long totalHundredths);
 
-void Process_outputRate(RichString* str, char* buffer, int n, double rate, int coloring);
+extern void Process_outputRate(RichString* str, char* buffer, int n, double rate, int coloring);
 
-void Process_writeField(Process* this, RichString* str, ProcessField field);
+extern void Process_writeField(Process* this, RichString* str, ProcessField field);
 
-void Process_display(Object* cast, RichString* out);
+extern void Process_display(Object* cast, RichString* out);
 
-void Process_done(Process* this);
+extern void Process_done(Process* this);
 
 extern ProcessClass Process_class;
 
-void Process_init(Process* this, struct Settings_* settings);
+extern void Process_init(Process* this, struct Settings_* settings);
 
-void Process_toggleTag(Process* this);
+extern void Process_toggleTag(Process* this);
 
-bool Process_setPriority(Process* this, int priority);
+extern bool Process_setPriority(Process* this, int priority);
 
-bool Process_changePriorityBy(Process* this, int delta);
+extern bool Process_changePriorityBy(Process* this, int delta);
 
-void Process_sendSignal(Process* this, int sgn);
+extern void Process_sendSignal(Process* this, int sgn);
 
-long Process_pidCompare(const void* v1, const void* v2);
+extern long Process_pidCompare(const void* v1, const void* v2);
 
-long Process_compare(const void* v1, const void* v2);
+extern long Process_compare(const void* v1, const void* v2);
 
 #endif
diff --git a/ProcessList.h b/ProcessList.h
index 572d4843..ddc6f3fa 100644
--- a/ProcessList.h
+++ b/ProcessList.h
@@ -71,32 +71,32 @@ void ProcessList_delete(ProcessList* pl);
 void ProcessList_goThroughEntries(ProcessList* pl);
 
 
-ProcessList* ProcessList_init(ProcessList* this, ObjectClass* klass, UsersTable* usersTable, Hashtable* pidWhiteList, uid_t userId);
+extern ProcessList* ProcessList_init(ProcessList* this, ObjectClass* klass, UsersTable* usersTable, Hashtable* pidWhiteList, uid_t userId);
 
-void ProcessList_done(ProcessList* this);
+extern void ProcessList_done(ProcessList* this);
 
-void ProcessList_setPanel(ProcessList* this, Panel* panel);
+extern void ProcessList_setPanel(ProcessList* this, Panel* panel);
 
-void ProcessList_printHeader(ProcessList* this, RichString* header);
+extern void ProcessList_printHeader(ProcessList* this, RichString* header);
 
-void ProcessList_add(ProcessList* this, Process* p);
+extern void ProcessList_add(ProcessList* this, Process* p);
 
-void ProcessList_remove(ProcessList* this, Process* p);
+extern void ProcessList_remove(ProcessList* this, Process* p);
 
-Process* ProcessList_get(ProcessList* this, int idx);
+extern Process* ProcessList_get(ProcessList* this, int idx);
 
-int ProcessList_size(ProcessList* this);
+extern int ProcessList_size(ProcessList* this);
 
-void ProcessList_sort(ProcessList* this);
+extern void ProcessList_sort(ProcessList* this);
 
-ProcessField ProcessList_keyAt(ProcessList* this, int at);
+extern ProcessField ProcessList_keyAt(ProcessList* this, int at);
 
-void ProcessList_expandTree(ProcessList* this);
+extern void ProcessList_expandTree(ProcessList* this);
 
-void ProcessList_rebuildPanel(ProcessList* this);
+extern void ProcessList_rebuildPanel(ProcessList* this);
 
-Process* ProcessList_getProcess(ProcessList* this, pid_t pid, bool* preExisting, Process_New constructor);
+extern Process* ProcessList_getProcess(ProcessList* this, pid_t pid, bool* preExisting, Process_New constructor);
 
-void ProcessList_scan(ProcessList* this);
+extern void ProcessList_scan(ProcessList* this);
 
 #endif
diff --git a/RichString.h b/RichString.h
index f5b5cba1..a294a550 100644
--- a/RichString.h
+++ b/RichString.h
@@ -71,24 +71,24 @@ typedef struct RichString_ {
 
 extern void RichString_setAttrn(RichString* this, int attrs, int start, int finish);
 
-int RichString_findChar(RichString* this, char c, int start);
+extern int RichString_findChar(RichString* this, char c, int start);
 
 #else
 
-void RichString_setAttrn(RichString* this, int attrs, int start, int finish);
+extern void RichString_setAttrn(RichString* this, int attrs, int start, int finish);
 
-int RichString_findChar(RichString* this, char c, int start);
+extern int RichString_findChar(RichString* this, char c, int start);
 
 #endif
 
-void RichString_prune(RichString* this);
+extern void RichString_prune(RichString* this);
 
-void RichString_setAttr(RichString* this, int attrs);
+extern void RichString_setAttr(RichString* this, int attrs);
 
-void RichString_append(RichString* this, int attrs, const char* data);
+extern void RichString_append(RichString* this, int attrs, const char* data);
 
-void RichString_appendn(RichString* this, int attrs, const char* data, int len);
+extern void RichString_appendn(RichString* this, int attrs, const char* data, int len);
 
-void RichString_write(RichString* this, int attrs, const char* data);
+extern void RichString_write(RichString* this, int attrs, const char* data);
 
 #endif
diff --git a/ScreenManager.h b/ScreenManager.h
index 3d02a883..b7b5617b 100644
--- a/ScreenManager.h
+++ b/ScreenManager.h
@@ -35,18 +35,18 @@ typedef struct ScreenManager_ {
 } ScreenManager;
 
 
-ScreenManager* ScreenManager_new(int x1, int y1, int x2, int y2, Orientation orientation, const Header* header, const Settings* settings, bool owner);
+extern ScreenManager* ScreenManager_new(int x1, int y1, int x2, int y2, Orientation orientation, const Header* header, const Settings* settings, bool owner);
 
-void ScreenManager_delete(ScreenManager* this);
+extern void ScreenManager_delete(ScreenManager* this);
 
 extern int ScreenManager_size(ScreenManager* this);
 
-void ScreenManager_add(ScreenManager* this, Panel* item, int size);
+extern void ScreenManager_add(ScreenManager* this, Panel* item, int size);
 
-Panel* ScreenManager_remove(ScreenManager* this, int idx);
+extern Panel* ScreenManager_remove(ScreenManager* this, int idx);
 
-void ScreenManager_resize(ScreenManager* this, int x1, int y1, int x2, int y2);
+extern void ScreenManager_resize(ScreenManager* this, int x1, int y1, int x2, int y2);
 
-void ScreenManager_run(ScreenManager* this, Panel** lastFocus, int* lastKey);
+extern void ScreenManager_run(ScreenManager* this, Panel** lastFocus, int* lastKey);
 
 #endif
diff --git a/Settings.h b/Settings.h
index d9dc0683..4f8722b3 100644
--- a/Settings.h
+++ b/Settings.h
@@ -58,12 +58,12 @@ typedef struct Settings_ {
 #endif
 
 
-void Settings_delete(Settings* this);
+extern void Settings_delete(Settings* this);
 
-bool Settings_write(Settings* this);
+extern bool Settings_write(Settings* this);
 
-Settings* Settings_new(int cpuCount);
+extern Settings* Settings_new(int cpuCount);
 
-void Settings_invertSortOrder(Settings* this);
+extern void Settings_invertSortOrder(Settings* this);
 
 #endif
diff --git a/SignalsPanel.h b/SignalsPanel.h
index da753546..8720376a 100644
--- a/SignalsPanel.h
+++ b/SignalsPanel.h
@@ -16,6 +16,6 @@ typedef struct SignalItem_ {
 } SignalItem;
 
 
-Panel* SignalsPanel_new();
+extern Panel* SignalsPanel_new();
 
 #endif
diff --git a/StringUtils.h b/StringUtils.h
index d3378b38..c1070d4f 100644
--- a/StringUtils.h
+++ b/StringUtils.h
@@ -19,18 +19,18 @@ in the source distribution for its full text.
  * at compile time (e.g. when they are immutable string literals). :)
  */
 
-char* String_cat(const char* s1, const char* s2);
+extern char* String_cat(const char* s1, const char* s2);
 
-char* String_trim(const char* in);
+extern char* String_trim(const char* in);
 
 extern int String_eq(const char* s1, const char* s2);
 
-char** String_split(const char* s, char sep, int* n);
+extern char** String_split(const char* s, char sep, int* n);
 
-void String_freeArray(char** s);
+extern void String_freeArray(char** s);
 
-char* String_getToken(const char* line, const unsigned short int numMatch);
+extern char* String_getToken(const char* line, const unsigned short int numMatch);
 
-char* String_readLine(FILE* fd);
+extern char* String_readLine(FILE* fd);
 
 #endif
diff --git a/TraceScreen.h b/TraceScreen.h
index 8845c51a..d43281d9 100644
--- a/TraceScreen.h
+++ b/TraceScreen.h
@@ -25,16 +25,16 @@ typedef struct TraceScreen_ {
 
 extern InfoScreenClass TraceScreen_class;
 
-TraceScreen* TraceScreen_new(Process* process);
+extern TraceScreen* TraceScreen_new(Process* process);
 
-void TraceScreen_delete(Object* cast);
+extern void TraceScreen_delete(Object* cast);
 
-void TraceScreen_draw(InfoScreen* this);
+extern void TraceScreen_draw(InfoScreen* this);
 
-bool TraceScreen_forkTracer(TraceScreen* this);
+extern bool TraceScreen_forkTracer(TraceScreen* this);
 
-void TraceScreen_updateTrace(InfoScreen* super);
+extern void TraceScreen_updateTrace(InfoScreen* super);
 
-bool TraceScreen_onKey(InfoScreen* super, int ch);
+extern bool TraceScreen_onKey(InfoScreen* super, int ch);
 
 #endif
diff --git a/UsersTable.h b/UsersTable.h
index 93ece0dc..9eba59ad 100644
--- a/UsersTable.h
+++ b/UsersTable.h
@@ -15,11 +15,11 @@ typedef struct UsersTable_ {
    Hashtable* users;
 } UsersTable;
 
-UsersTable* UsersTable_new();
+extern UsersTable* UsersTable_new();
 
-void UsersTable_delete(UsersTable* this);
+extern void UsersTable_delete(UsersTable* this);
 
-char* UsersTable_getRef(UsersTable* this, unsigned int uid);
+extern char* UsersTable_getRef(UsersTable* this, unsigned int uid);
 
 extern void UsersTable_foreach(UsersTable* this, Hashtable_PairFunction f, void* userData);
 
diff --git a/Vector.h b/Vector.h
index 85939bf1..b48c8363 100644
--- a/Vector.h
+++ b/Vector.h
@@ -27,38 +27,38 @@ typedef struct Vector_ {
 } Vector;
 
 
-Vector* Vector_new(ObjectClass* type, bool owner, int size);
+extern Vector* Vector_new(ObjectClass* type, bool owner, int size);
 
-void Vector_delete(Vector* this);
+extern void Vector_delete(Vector* this);
 
 #ifdef DEBUG
 
-int Vector_count(Vector* this);
+extern int Vector_count(Vector* this);
 
 #endif
 
-void Vector_prune(Vector* this);
+extern void Vector_prune(Vector* this);
 
 // If I were to use only one sorting algorithm for both cases, it would probably be this one:
 /*
 
 */
 
-void Vector_quickSort(Vector* this);
+extern void Vector_quickSort(Vector* this);
 
-void Vector_insertionSort(Vector* this);
+extern void Vector_insertionSort(Vector* this);
 
-void Vector_insert(Vector* this, int idx, void* data_);
+extern void Vector_insert(Vector* this, int idx, void* data_);
 
-Object* Vector_take(Vector* this, int idx);
+extern Object* Vector_take(Vector* this, int idx);
 
-Object* Vector_remove(Vector* this, int idx);
+extern Object* Vector_remove(Vector* this, int idx);
 
-void Vector_moveUp(Vector* this, int idx);
+extern void Vector_moveUp(Vector* this, int idx);
 
-void Vector_moveDown(Vector* this, int idx);
+extern void Vector_moveDown(Vector* this, int idx);
 
-void Vector_set(Vector* this, int idx, void* data_);
+extern void Vector_set(Vector* this, int idx, void* data_);
 
 #ifdef DEBUG
 
@@ -84,7 +84,7 @@ extern int Vector_size(Vector* this);
 
 */
 
-void Vector_add(Vector* this, void* data_);
+extern void Vector_add(Vector* this, void* data_);
 
 extern int Vector_indexOf(Vector* this, void* search_, Object_Compare compare);
 
diff --git a/XAlloc.h b/XAlloc.h
index 2ebee1a8..97a1c0d0 100644
--- a/XAlloc.h
+++ b/XAlloc.h
@@ -11,11 +11,11 @@
 #include <assert.h>
 #include <stdlib.h>
 
-void* xMalloc(size_t size);
+extern void* xMalloc(size_t size);
 
-void* xCalloc(size_t nmemb, size_t size);
+extern void* xCalloc(size_t nmemb, size_t size);
 
-void* xRealloc(void* ptr, size_t size);
+extern void* xRealloc(void* ptr, size_t size);
 
 #define xSnprintf(fmt, len, ...) do { int _l=len; int _n=snprintf(fmt, _l, __VA_ARGS__); if (!(_n > -1 && _n < _l)) { curs_set(1); endwin(); err(1, NULL); } } while(0)
 
@@ -32,9 +32,9 @@ void* xRealloc(void* ptr, size_t size);
 #endif
 #if (__has_attribute(nonnull) || \
     ((__GNUC__ > 3) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 3)))
-char* xStrdup_(const char* str) __attribute__((nonnull));
+extern char* xStrdup_(const char* str) __attribute__((nonnull));
 #endif // __has_attribute(nonnull) || GNU C 3.3 or later
 
-char* xStrdup_(const char* str);
+extern char* xStrdup_(const char* str);
 
 #endif
diff --git a/htop.h b/htop.h
index 7faa6c64..26c19180 100644
--- a/htop.h
+++ b/htop.h
@@ -14,6 +14,6 @@ in the source distribution for its full text.
 // ----------------------------------------
 
 
-int main(int argc, char** argv);
+extern int main(int argc, char** argv);
 
 #endif
diff --git a/linux/Battery.h b/linux/Battery.h
index cfb6c324..261cff05 100644
--- a/linux/Battery.h
+++ b/linux/Battery.h
@@ -29,6 +29,6 @@ Linux battery readings written by Ian P. Hands (iphands@gmail.com, ihands@redhat
 // READ FROM /sys
 // ----------------------------------------
 
-void Battery_getData(double* level, ACPresence* isOnAC);
+extern void Battery_getData(double* level, ACPresence* isOnAC);
 
 #endif
diff --git a/linux/IOPriorityPanel.h b/linux/IOPriorityPanel.h
index 9f77a4d9..0bf74f50 100644
--- a/linux/IOPriorityPanel.h
+++ b/linux/IOPriorityPanel.h
@@ -13,9 +13,9 @@ in the source distribution for its full text.
 #include "IOPriority.h"
 #include "ListItem.h"
 
-Panel* IOPriorityPanel_new(IOPriority currPrio);
+extern Panel* IOPriorityPanel_new(IOPriority currPrio);
 
-IOPriority IOPriorityPanel_getIOPriority(Panel* this);
+extern IOPriority IOPriorityPanel_getIOPriority(Panel* this);
 
 
 #endif
diff --git a/linux/LinuxCRT.h b/linux/LinuxCRT.h
index f8c43e4d..966dfecf 100644
--- a/linux/LinuxCRT.h
+++ b/linux/LinuxCRT.h
@@ -12,6 +12,6 @@ in the source distribution for its full text.
 #ifdef HAVE_EXECINFO_H
 #endif
 
-void CRT_handleSIGSEGV(int sgn);
+extern void CRT_handleSIGSEGV(int sgn);
 
 #endif
diff --git a/linux/LinuxProcessList.h b/linux/LinuxProcessList.h
index f30b487d..cf369e38 100644
--- a/linux/LinuxProcessList.h
+++ b/linux/LinuxProcessList.h
@@ -98,9 +98,9 @@ typedef struct LinuxProcessList_ {
 
 #endif
 
-ProcessList* ProcessList_new(UsersTable* usersTable, Hashtable* pidWhiteList, uid_t userId);
+extern ProcessList* ProcessList_new(UsersTable* usersTable, Hashtable* pidWhiteList, uid_t userId);
 
-void ProcessList_delete(ProcessList* pl);
+extern void ProcessList_delete(ProcessList* pl);
 
 
 #ifdef HAVE_TASKSTATS
@@ -123,6 +123,6 @@ void ProcessList_delete(ProcessList* pl);
 
 #endif
 
-void ProcessList_goThroughEntries(ProcessList* super);
+extern void ProcessList_goThroughEntries(ProcessList* super);
 
 #endif
diff --git a/linux/Platform.h b/linux/Platform.h
index b0456e5b..89b0a301 100644
--- a/linux/Platform.h
+++ b/linux/Platform.h
@@ -27,22 +27,22 @@ extern const SignalItem Platform_signals[];
 
 extern const unsigned int Platform_numberOfSignals;
 
-void Platform_setBindings(Htop_Action* keys);
+extern void Platform_setBindings(Htop_Action* keys);
 
 extern MeterClass* Platform_meterTypes[];
 
-int Platform_getUptime();
+extern int Platform_getUptime();
 
-void Platform_getLoadAverage(double* one, double* five, double* fifteen);
+extern void Platform_getLoadAverage(double* one, double* five, double* fifteen);
 
-int Platform_getMaxPid();
+extern int Platform_getMaxPid();
 
-double Platform_setCPUValues(Meter* this, int cpu);
+extern double Platform_setCPUValues(Meter* this, int cpu);
 
-void Platform_setMemoryValues(Meter* this);
+extern void Platform_setMemoryValues(Meter* this);
 
-void Platform_setSwapValues(Meter* this);
+extern void Platform_setSwapValues(Meter* this);
 
-char* Platform_getProcessEnv(pid_t pid);
+extern char* Platform_getProcessEnv(pid_t pid);
 
 #endif