diff --git a/Action.c b/Action.c
index f36e0bd2..62266084 100644
--- a/Action.c
+++ b/Action.c
@@ -73,9 +73,9 @@ Object* Action_pickFromVector(State* st, Panel* list, int x, bool followProcess)
 
 // ----------------------------------------
 
-static void Action_runSetup(Settings* settings, const Header* header, ProcessList* pl) {
+static void Action_runSetup(Settings* settings, Header* header, ProcessList* pl) {
    ScreenManager* scr = ScreenManager_new(0, header->height, 0, -1, HORIZONTAL, header, settings, true);
-   CategoriesPanel* panelCategories = CategoriesPanel_new(scr, settings, (Header*) header, pl);
+   CategoriesPanel* panelCategories = CategoriesPanel_new(scr, settings, header, pl);
    ScreenManager_add(scr, (Panel*) panelCategories, 16);
    CategoriesPanel_makeMetersPage(panelCategories);
    Panel* panelFocus;
diff --git a/AffinityPanel.c b/AffinityPanel.c
index 57e889aa..1cae4ee4 100644
--- a/AffinityPanel.c
+++ b/AffinityPanel.c
@@ -19,8 +19,8 @@ in the source distribution for its full text.
 
 typedef struct MaskItem_ {
    Object super;
-   const char* text;
-   const char* indent; /* used also as an condition whether this is a tree node */
+   char* text;
+   char* indent; /* used also as an condition whether this is a tree node */
    int value; /* tri-state: 0 - off, 1 - some set, 2 - all set */
    int sub_tree; /* tri-state: 0 - no sub-tree, 1 - open sub-tree, 2 - closed sub-tree */
    Vector *children;
@@ -34,9 +34,8 @@ typedef struct MaskItem_ {
 
 static void MaskItem_delete(Object* cast) {
    MaskItem* this = (MaskItem*) cast;
-   free((void*)this->text);
-   if (this->indent)
-      free((void*)this->indent);
+   free(this->text);
+   free(this->indent);
    Vector_delete(this->children);
    #ifdef HAVE_LIBHWLOC
    if (this->ownCpuset)
diff --git a/DisplayOptionsPanel.c b/DisplayOptionsPanel.c
index 6978e238..37b5bcd0 100644
--- a/DisplayOptionsPanel.c
+++ b/DisplayOptionsPanel.c
@@ -43,9 +43,9 @@ static HandlerResult DisplayOptionsPanel_eventHandler(Panel* super, int ch) {
 
    if (result == HANDLED) {
       this->settings->changed = true;
-      const Header* header = this->scr->header;
-      Header_calculateHeight((Header*) header);
-      Header_reinit((Header*) header);
+      Header* header = this->scr->header;
+      Header_calculateHeight(header);
+      Header_reinit(header);
       Header_draw(header);
       ScreenManager_resize(this->scr, this->scr->x1, header->height, this->scr->x2, this->scr->y2);
    }
diff --git a/ListItem.c b/ListItem.c
index 73129fa9..8d26d7f0 100644
--- a/ListItem.c
+++ b/ListItem.c
@@ -70,7 +70,7 @@ const char* ListItem_getRef(ListItem* this) {
 }
 
 long ListItem_compare(const void* cast1, const void* cast2) {
-   ListItem* obj1 = (ListItem*) cast1;
-   ListItem* obj2 = (ListItem*) cast2;
+   const ListItem* obj1 = (const ListItem*) cast1;
+   const ListItem* obj2 = (const ListItem*) cast2;
    return strcmp(obj1->value, obj2->value);
 }
diff --git a/MetersPanel.c b/MetersPanel.c
index 1e0afcdc..c82ba48b 100644
--- a/MetersPanel.c
+++ b/MetersPanel.c
@@ -177,7 +177,7 @@ static HandlerResult MetersPanel_eventHandler(Panel* super, int ch) {
       }
    }
    if (result == HANDLED || sideMove) {
-      Header* header = (Header*) this->scr->header;
+      Header* header = this->scr->header;
       this->settings->changed = true;
       Header_calculateHeight(header);
       Header_draw(header);
diff --git a/Process.c b/Process.c
index 839db8d7..3c404db3 100644
--- a/Process.c
+++ b/Process.c
@@ -431,20 +431,20 @@ bool Process_sendSignal(Process* this, Arg sgn) {
 }
 
 long Process_pidCompare(const void* v1, const void* v2) {
-   Process* p1 = (Process*)v1;
-   Process* p2 = (Process*)v2;
+   const Process* p1 = (const Process*)v1;
+   const Process* p2 = (const Process*)v2;
    return (p1->pid - p2->pid);
 }
 
 long Process_compare(const void* v1, const void* v2) {
-   Process *p1, *p2;
-   Settings *settings = ((Process*)v1)->settings;
+   const Process *p1, *p2;
+   const Settings *settings = ((const Process*)v1)->settings;
    if (settings->direction == 1) {
-      p1 = (Process*)v1;
-      p2 = (Process*)v2;
+      p1 = (const Process*)v1;
+      p2 = (const Process*)v2;
    } else {
-      p2 = (Process*)v1;
-      p1 = (Process*)v2;
+      p2 = (const Process*)v1;
+      p1 = (const Process*)v2;
    }
    switch (settings->sortKey) {
    case PERCENT_CPU:
diff --git a/ScreenManager.c b/ScreenManager.c
index 92e792b4..2a2cb1d0 100644
--- a/ScreenManager.c
+++ b/ScreenManager.c
@@ -17,7 +17,7 @@ in the source distribution for its full text.
 #include <stdbool.h>
 
 
-ScreenManager* ScreenManager_new(int x1, int y1, int x2, int y2, Orientation orientation, const Header* header, const Settings* settings, bool owner) {
+ScreenManager* ScreenManager_new(int x1, int y1, int x2, int y2, Orientation orientation, Header* header, const Settings* settings, bool owner) {
    ScreenManager* this;
    this = xMalloc(sizeof(ScreenManager));
    this->x1 = x1;
diff --git a/ScreenManager.h b/ScreenManager.h
index 3c19a05d..6f19ab8f 100644
--- a/ScreenManager.h
+++ b/ScreenManager.h
@@ -25,13 +25,13 @@ typedef struct ScreenManager_ {
    Orientation orientation;
    Vector* panels;
    int panelCount;
-   const Header* header;
+   Header* header;
    const Settings* settings;
    bool owner;
    bool allowFocusChange;
 } ScreenManager;
 
-ScreenManager* ScreenManager_new(int x1, int y1, int x2, int y2, Orientation orientation, const Header* header, const Settings* settings, bool owner);
+ScreenManager* ScreenManager_new(int x1, int y1, int x2, int y2, Orientation orientation, Header* header, const Settings* settings, bool owner);
 
 void ScreenManager_delete(ScreenManager* this);
 
diff --git a/linux/Battery.c b/linux/Battery.c
index 6ea48c45..a0a0e58e 100644
--- a/linux/Battery.c
+++ b/linux/Battery.c
@@ -120,7 +120,7 @@ static ACPresence procAcpiCheck(void) {
       fclose(file);
       if (!line) continue;
 
-      const char *isOnline = String_getToken(line, 2);
+      char *isOnline = String_getToken(line, 2);
       free(line);
 
       if (strcmp(isOnline, "on-line") == 0) {
@@ -128,7 +128,7 @@ static ACPresence procAcpiCheck(void) {
       } else {
          isOn = AC_ABSENT;
       }
-      free((char *) isOnline);
+      free(isOnline);
       if (isOn == AC_PRESENT) {
          break;
       }
@@ -193,9 +193,9 @@ static void Battery_getSysData(double* level, ACPresence* isOnAC) {
       if (!dirEntry)
          break;
       char* entryName = (char *) dirEntry->d_name;
-      const char filePath[256];
+      char filePath[256];
 
-      xSnprintf((char *) filePath, sizeof filePath, SYS_POWERSUPPLY_DIR "/%s/type", entryName);
+      xSnprintf(filePath, sizeof filePath, SYS_POWERSUPPLY_DIR "/%s/type", entryName);
       int fd1 = open(filePath, O_RDONLY);
       if (fd1 == -1)
          continue;
@@ -207,7 +207,7 @@ static void Battery_getSysData(double* level, ACPresence* isOnAC) {
          continue;
 
       if (type[0] == 'B' && type[1] == 'a' && type[2] == 't') {
-         xSnprintf((char *) filePath, sizeof filePath, SYS_POWERSUPPLY_DIR "/%s/uevent", entryName);
+         xSnprintf(filePath, sizeof filePath, SYS_POWERSUPPLY_DIR "/%s/uevent", entryName);
          int fd2 = open(filePath, O_RDONLY);
          if (fd2 == -1) {
             closedir(dir);
@@ -260,7 +260,7 @@ static void Battery_getSysData(double* level, ACPresence* isOnAC) {
             continue;
          }
 
-         xSnprintf((char *) filePath, sizeof filePath, SYS_POWERSUPPLY_DIR "/%s/online", entryName);
+         xSnprintf(filePath, sizeof filePath, SYS_POWERSUPPLY_DIR "/%s/online", entryName);
          int fd3 = open(filePath, O_RDONLY);
          if (fd3 == -1) {
             closedir(dir);
diff --git a/linux/LinuxProcess.c b/linux/LinuxProcess.c
index a589d62e..41404de1 100644
--- a/linux/LinuxProcess.c
+++ b/linux/LinuxProcess.c
@@ -297,14 +297,14 @@ void LinuxProcess_writeField(Process* this, RichString* str, ProcessField field)
 }
 
 long LinuxProcess_compare(const void* v1, const void* v2) {
-   LinuxProcess *p1, *p2;
-   Settings *settings = ((Process*)v1)->settings;
+   const LinuxProcess *p1, *p2;
+   const Settings *settings = ((const Process*)v1)->settings;
    if (settings->direction == 1) {
-      p1 = (LinuxProcess*)v1;
-      p2 = (LinuxProcess*)v2;
+      p1 = (const LinuxProcess*)v1;
+      p2 = (const LinuxProcess*)v2;
    } else {
-      p2 = (LinuxProcess*)v1;
-      p1 = (LinuxProcess*)v2;
+      p2 = (const LinuxProcess*)v1;
+      p1 = (const LinuxProcess*)v2;
    }
    long long diff;
    switch ((int)settings->sortKey) {
diff --git a/linux/LinuxProcessList.c b/linux/LinuxProcessList.c
index 807cc8a6..76f2a423 100644
--- a/linux/LinuxProcessList.c
+++ b/linux/LinuxProcessList.c
@@ -59,8 +59,8 @@ static ssize_t xread(int fd, void *buf, size_t count) {
 }
 
 static int sortTtyDrivers(const void* va, const void* vb) {
-   TtyDriver* a = (TtyDriver*) va;
-   TtyDriver* b = (TtyDriver*) vb;
+   const TtyDriver* a = (const TtyDriver*) va;
+   const TtyDriver* b = (const TtyDriver*) vb;
    return (a->major == b->major) ? ((int)a->minorFrom - (int)b->minorFrom) : ((int)a->major - (int)b->major);
 }