diff --git a/lib/system/threads.nim b/lib/system/threads.nim
index 2c2fd4325..050950121 100644
--- a/lib/system/threads.nim
+++ b/lib/system/threads.nim
@@ -146,7 +146,7 @@ proc threadProcWrapStackFrame[TArg](thrd: ptr Thread[TArg]) =
   when defined(boehmgc):
     boehmGC_call_with_stack_base(threadProcWrapDispatch[TArg], thrd)
   elif not defined(nogc) and not defined(gogc) and not defined(gcRegions) and not defined(gcDestructors):
-    var p {.volatile.}: proc(a: ptr Thread[TArg]) {.nimcall.} =
+    var p {.volatile.}: proc(a: ptr Thread[TArg]) {.nimcall, gcsafe.} =
       threadProcWrapDispatch[TArg]
     # init the GC for refc/markandsweep
     nimGC_setStackBottom(addr(p))