diff --git a/src/process/ntapi_tt_fork.c b/src/process/ntapi_tt_fork.c
index b7a7a20..7483657 100644
--- a/src/process/ntapi_tt_fork.c
+++ b/src/process/ntapi_tt_fork.c
@@ -15,6 +15,9 @@
 #include <ntapi/ntapi.h>
 #include "ntapi_impl.h"
 
+#define __FORK_THREAD_STACK_COMMIT  (0x10000)
+#define __FORK_THREAD_STACK_RESERVE (0x20000)
+
 static intptr_t	__fork_retry_stats  = 0;
 static intptr_t	__fork_resume_stats = 0;
 
@@ -168,8 +171,8 @@ static int32_t __fastcall __ntapi_tt_fork_child(
 
 	tparams.start			= __fork_thread;
 	tparams.arg			= &state;
-	tparams.stack_size_commit	= 0x10000;
-	tparams.stack_size_reserve	= 0x20000;
+	tparams.stack_size_commit	= __FORK_THREAD_STACK_COMMIT;
+	tparams.stack_size_reserve	= __FORK_THREAD_STACK_RESERVE;
 
 	status = __ntapi->tt_create_local_thread(
 		&tparams);