diff --git a/bootstrap/unix-44/SYSTEM.h b/bootstrap/unix-44/SYSTEM.h
index 130a7f9b..1c0b07fd 100644
--- a/bootstrap/unix-44/SYSTEM.h
+++ b/bootstrap/unix-44/SYSTEM.h
@@ -32,6 +32,8 @@ typedef unsigned char        SYSTEM_CARD8;
   typedef unsigned int         size_t;
 #endif
 
+#define _SIZE_T_DEFINED_  // For OpenBSD
+
 void *memcpy(void *dest, const void *source, size_t size);
 
 
diff --git a/bootstrap/unix-48/SYSTEM.h b/bootstrap/unix-48/SYSTEM.h
index 130a7f9b..1c0b07fd 100644
--- a/bootstrap/unix-48/SYSTEM.h
+++ b/bootstrap/unix-48/SYSTEM.h
@@ -32,6 +32,8 @@ typedef unsigned char        SYSTEM_CARD8;
   typedef unsigned int         size_t;
 #endif
 
+#define _SIZE_T_DEFINED_  // For OpenBSD
+
 void *memcpy(void *dest, const void *source, size_t size);
 
 
diff --git a/bootstrap/unix-88/SYSTEM.h b/bootstrap/unix-88/SYSTEM.h
index 130a7f9b..1c0b07fd 100644
--- a/bootstrap/unix-88/SYSTEM.h
+++ b/bootstrap/unix-88/SYSTEM.h
@@ -32,6 +32,8 @@ typedef unsigned char        SYSTEM_CARD8;
   typedef unsigned int         size_t;
 #endif
 
+#define _SIZE_T_DEFINED_  // For OpenBSD
+
 void *memcpy(void *dest, const void *source, size_t size);
 
 
diff --git a/bootstrap/windows-48/Platform.c b/bootstrap/windows-48/Platform.c
index bc7ebab6..75b51a60 100644
--- a/bootstrap/windows-48/Platform.c
+++ b/bootstrap/windows-48/Platform.c
@@ -109,7 +109,7 @@ export BOOLEAN Platform_getEnv (CHAR *var, LONGINT var__len, CHAR *val, LONGINT
 #define Platform_ERRORWRITEPROTECT()	ERROR_WRITE_PROTECT
 #define Platform_ETIMEDOUT()	WSAETIMEDOUT
 extern void Heap_InitHeap();
-#define Platform_GetTickCount()	(LONGINT)(uint32_t)GetTickCount()
+#define Platform_GetTickCount()	(LONGINT)(SYSTEM_CARD32)GetTickCount()
 #define Platform_HeapInitHeap()	Heap_InitHeap()
 #define Platform_SetInterruptHandler(h)	SystemSetInterruptHandler((uintptr_t)h)
 #define Platform_SetQuitHandler(h)	SystemSetQuitHandler((uintptr_t)h)
diff --git a/bootstrap/windows-48/SYSTEM.h b/bootstrap/windows-48/SYSTEM.h
index 130a7f9b..1c0b07fd 100644
--- a/bootstrap/windows-48/SYSTEM.h
+++ b/bootstrap/windows-48/SYSTEM.h
@@ -32,6 +32,8 @@ typedef unsigned char        SYSTEM_CARD8;
   typedef unsigned int         size_t;
 #endif
 
+#define _SIZE_T_DEFINED_  // For OpenBSD
+
 void *memcpy(void *dest, const void *source, size_t size);
 
 
diff --git a/bootstrap/windows-88/Platform.c b/bootstrap/windows-88/Platform.c
index fa1e8052..c8530dd0 100644
--- a/bootstrap/windows-88/Platform.c
+++ b/bootstrap/windows-88/Platform.c
@@ -110,7 +110,7 @@ export BOOLEAN Platform_getEnv (CHAR *var, LONGINT var__len, CHAR *val, LONGINT
 #define Platform_ERRORWRITEPROTECT()	ERROR_WRITE_PROTECT
 #define Platform_ETIMEDOUT()	WSAETIMEDOUT
 extern void Heap_InitHeap();
-#define Platform_GetTickCount()	(LONGINT)(uint32_t)GetTickCount()
+#define Platform_GetTickCount()	(LONGINT)(SYSTEM_CARD32)GetTickCount()
 #define Platform_HeapInitHeap()	Heap_InitHeap()
 #define Platform_SetInterruptHandler(h)	SystemSetInterruptHandler((uintptr_t)h)
 #define Platform_SetQuitHandler(h)	SystemSetQuitHandler((uintptr_t)h)
diff --git a/bootstrap/windows-88/SYSTEM.h b/bootstrap/windows-88/SYSTEM.h
index 130a7f9b..1c0b07fd 100644
--- a/bootstrap/windows-88/SYSTEM.h
+++ b/bootstrap/windows-88/SYSTEM.h
@@ -32,6 +32,8 @@ typedef unsigned char        SYSTEM_CARD8;
   typedef unsigned int         size_t;
 #endif
 
+#define _SIZE_T_DEFINED_  // For OpenBSD
+
 void *memcpy(void *dest, const void *source, size_t size);
 
 
diff --git a/src/system/Platformwindows.Mod b/src/system/Platformwindows.Mod
index 0e30e3f9..3395e57b 100644
--- a/src/system/Platformwindows.Mod
+++ b/src/system/Platformwindows.Mod
@@ -232,7 +232,7 @@ BEGIN
   YMDHMStoClock(styear(), stmon(), stmday(), sthour(), stmin(), stsec(), t, d);
 END GetClock;
 
-PROCEDURE -GetTickCount(): LONGINT "(LONGINT)(uint32_t)GetTickCount()";
+PROCEDURE -GetTickCount(): LONGINT "(LONGINT)(SYSTEM_CARD32)GetTickCount()";
 
 PROCEDURE Time*(): LONGINT;
 VAR ms: LONGINT;