diff --git a/lib/system/threads.nim b/lib/system/threads.nim
index 496c31af14..4e07200072 100644
--- a/lib/system/threads.nim
+++ b/lib/system/threads.nim
@@ -95,7 +95,9 @@ when defined(windows):
       importc: "TlsGetValue", stdcall, dynlib: "kernel32".}
   
 else:
-  {.passL: "-pthread".}
+  when not defined(macosx):
+    {.passL: "-pthread".}
+
   {.passC: "-pthread".}
 
   type