diff --git a/rtl/go32v2/tthread.inc b/rtl/go32v2/tthread.inc
index 85c59ded20..844960060b 100644
--- a/rtl/go32v2/tthread.inc
+++ b/rtl/go32v2/tthread.inc
@@ -46,7 +46,7 @@ begin
 end;
 
 
-constructor TThread.Create(CreateSuspended: Boolean);
+constructor TThread.Create(CreateSuspended: Boolean; const StackSize: DWord = DefaultStackSize);
 
 begin
  {IsMultiThread := TRUE; }
diff --git a/rtl/openbsd/tthread.inc b/rtl/openbsd/tthread.inc
index 5900095344..a523c7e7dd 100644
--- a/rtl/openbsd/tthread.inc
+++ b/rtl/openbsd/tthread.inc
@@ -186,7 +186,7 @@ begin
 end;
 
 { TThread }
-constructor TThread.Create(CreateSuspended: Boolean);
+constructor TThread.Create(CreateSuspended: Boolean; const StackSize: DWord = DefaultStackSize);
 begin
   // lets just hope that the user doesn't create a thread
   // via BeginThread and creates the first TThread Object in there!
@@ -198,7 +198,7 @@ begin
   FInitialSuspended := CreateSuspended;
   FFatalException := nil;
   WRITE_DEBUG('creating thread, self = ',longint(self));
-  FHandle:= BeginThread(@ThreadFunc, Pointer(Self), FThreadID);
+  FHandle:= BeginThread(@ThreadFunc, Pointer(Self), FThreadID, StackSize);
   WRITE_DEBUG('TThread.Create done');
 end;
 
diff --git a/rtl/wince/tthread.inc b/rtl/wince/tthread.inc
index d2a2ce3d0c..528a8349a7 100644
--- a/rtl/wince/tthread.inc
+++ b/rtl/wince/tthread.inc
@@ -114,7 +114,7 @@ begin
   if FreeThread then Thread.Free;
 end;
 
-constructor TThread.Create(CreateSuspended: Boolean);
+constructor TThread.Create(CreateSuspended: Boolean; const StackSize: DWord = DefaultStackSize);
 var
   Flags: Integer;
 begin
@@ -123,7 +123,7 @@ begin
   FSuspended := CreateSuspended;
   Flags := 0;
   if CreateSuspended then Flags := CREATE_SUSPENDED;
-  FHandle := BeginThread(nil, 0, @ThreadProc, pointer(self), Flags, FThreadID);
+  FHandle := BeginThread(nil, StackSize, @ThreadProc, pointer(self), Flags, FThreadID);
   FFatalException := nil;
 end;