diff --git a/Process.c b/Process.c
index 46082173..b1412d95 100644
--- a/Process.c
+++ b/Process.c
@@ -495,7 +495,6 @@ long Process_pidCompare(const void* v1, const void* v2) {
 long Process_compare(const void* v1, const void* v2) {
    const Process *p1, *p2;
    const Settings *settings = ((const Process*)v1)->settings;
-   int r;
 
    if (Settings_getActiveDirection(settings) == 1) {
       p1 = (const Process*)v1;
@@ -507,7 +506,19 @@ long Process_compare(const void* v1, const void* v2) {
 
    ProcessField key = Settings_getActiveSortKey(settings);
 
-   switch (key) {
+   long result = Process_compareByKey(p1, p2, key);
+
+   // Implement tie-breaker (needed to make tree mode more stable)
+   if (!result)
+      result = SPACESHIP_NUMBER(p1->pid, p2->pid);
+
+   return result;
+}
+
+long Process_compareByKey_Base(const Process* p1, const Process* p2, ProcessField key) {
+   int r;
+
+   switch ((int) key) {
    case PERCENT_CPU:
    case PERCENT_NORM_CPU:
       return SPACESHIP_NUMBER(p2->percent_cpu, p1->percent_cpu);
@@ -557,6 +568,6 @@ long Process_compare(const void* v1, const void* v2) {
    case USER:
       return SPACESHIP_NULLSTR(p1->user, p2->user);
    default:
-      return Process_compareByKey(p1, p2, key);
+      return SPACESHIP_NUMBER(p1->pid, p2->pid);
    }
 }
diff --git a/Process.h b/Process.h
index 9e800891..b58135ed 100644
--- a/Process.h
+++ b/Process.h
@@ -142,7 +142,7 @@ typedef struct ProcessClass_ {
 #define As_Process(this_)                              ((const ProcessClass*)((this_)->super.klass))
 
 #define Process_getCommand(this_)                      (As_Process(this_)->getCommandStr ? As_Process(this_)->getCommandStr((const Process*)(this_)) : ((const Process*)(this_))->comm)
-#define Process_compareByKey(p1_, p2_, key_)           (As_Process(p1_)->compareByKey ? (As_Process(p1_)->compareByKey(p1_, p2_, key_)) : SPACESHIP_NUMBER(p1->pid, p2->pid))
+#define Process_compareByKey(p1_, p2_, key_)           (As_Process(p1_)->compareByKey ? (As_Process(p1_)->compareByKey(p1_, p2_, key_)) : Process_compareByKey_Base(p1_, p2_, key_))
 
 static inline pid_t Process_getParentPid(const Process* this) {
    return this->tgid == this->pid ? this->ppid : this->tgid;
@@ -199,4 +199,6 @@ bool Process_sendSignal(Process* this, Arg sgn);
 
 long Process_pidCompare(const void* v1, const void* v2);
 
+long Process_compareByKey_Base(const Process* p1, const Process* p2, ProcessField key);
+
 #endif
diff --git a/darwin/DarwinProcess.c b/darwin/DarwinProcess.c
index 38e2a234..c463193b 100644
--- a/darwin/DarwinProcess.c
+++ b/darwin/DarwinProcess.c
@@ -92,7 +92,7 @@ static long DarwinProcess_compareByKey(const Process* v1, const Process* v2, Pro
    case TRANSLATED:
       return SPACESHIP_NUMBER(p1->translated, p2->translated);
    default:
-      return SPACESHIP_NUMBER(v1->pid, v2->pid);
+      return Process_compareByKey_Base(v1, v2, key);
    }
 }
 
diff --git a/dragonflybsd/DragonFlyBSDProcess.c b/dragonflybsd/DragonFlyBSDProcess.c
index 1f08530f..32ca12fd 100644
--- a/dragonflybsd/DragonFlyBSDProcess.c
+++ b/dragonflybsd/DragonFlyBSDProcess.c
@@ -120,7 +120,7 @@ long DragonFlyBSDProcess_compareByKey(const Process* v1, const Process* v2, Proc
    case JAIL:
       return SPACESHIP_NULLSTR(p1->jname, p2->jname);
    default:
-      return SPACESHIP_NULLSTR(v1->pid, v2->pid);
+      return Process_compareByKey_Base(v1, v2, key);
    }
 }
 
diff --git a/freebsd/FreeBSDProcess.c b/freebsd/FreeBSDProcess.c
index cebf6908..a7c079c0 100644
--- a/freebsd/FreeBSDProcess.c
+++ b/freebsd/FreeBSDProcess.c
@@ -121,7 +121,7 @@ static long FreeBSDProcess_compareByKey(const Process* v1, const Process* v2, Pr
    case TTY_NR:
       return SPACESHIP_NULLSTR(p1->ttyPath, p2->ttyPath);
    default:
-      return SPACESHIP_NUMBER(v1->pid, v2->pid);
+      return Process_compareByKey_Base(v1, v2, key);
    }
 }
 
diff --git a/linux/LinuxProcess.c b/linux/LinuxProcess.c
index 9e184b64..72955c8f 100644
--- a/linux/LinuxProcess.c
+++ b/linux/LinuxProcess.c
@@ -857,7 +857,7 @@ static long LinuxProcess_compareByKey(const Process* v1, const Process* v2, Proc
    case CWD:
       return SPACESHIP_NULLSTR(p1->cwd, p2->cwd);
    default:
-      return SPACESHIP_NUMBER(v1->pid, v2->pid);
+      return Process_compareByKey_Base(v1, v2, key);
    }
 }
 
diff --git a/openbsd/OpenBSDProcess.c b/openbsd/OpenBSDProcess.c
index 532093f1..9756f9bb 100644
--- a/openbsd/OpenBSDProcess.c
+++ b/openbsd/OpenBSDProcess.c
@@ -222,7 +222,7 @@ static long OpenBSDProcess_compareByKey(const Process* v1, const Process* v2, Pr
    switch ((int) key) {
    // add OpenBSD-specific fields here
    default:
-      return SPACESHIP_NUMBER(v1->pid, v2->pid);
+      return Process_compareByKey_Base(v1, v2, key);
    }
 }
 
diff --git a/solaris/SolarisProcess.c b/solaris/SolarisProcess.c
index e6c49936..f6470a3c 100644
--- a/solaris/SolarisProcess.c
+++ b/solaris/SolarisProcess.c
@@ -142,7 +142,7 @@ long SolarisProcess_compareByKey(const void* v1, const void* v2, ProcessField ke
    case LWPID:
       return SPACESHIP_NUMBER(p1->lwpid, p2->lwpid);
    default:
-      return SPACESHIP_NUMBER(v1->pid, v2->pid);
+      return Process_compareByKey_Base(v1, v2, key);
    }
 }