diff --git a/Source/NSThread.m b/Source/NSThread.m
index a43e04ff8..7c3bf9253 100644
--- a/Source/NSThread.m
+++ b/Source/NSThread.m
@@ -175,8 +175,12 @@ void gnustep_base_thread_callback()
       // sleep 30 minutes
 #ifdef	HAVE_USLEEP
       usleep (30*60*1000000);
+#else
+#if defined(__WIN32__) || defined(_WIN32)
+      Sleep (30*60*1000);
 #else
       sleep (30*60);
+#endif
 #endif
       delay = [date timeIntervalSinceNow];
     }
@@ -186,8 +190,12 @@ void gnustep_base_thread_callback()
     {
 #ifdef	HAVE_USLEEP
       usleep ((int)(delay*1000000));
+#else
+#if defined(__WIN32__) || defined(_WIN32)
+      Sleep (delay*1000);
 #else
       sleep ((int)delay);
+#endif
 #endif
       delay = [date timeIntervalSinceNow];
     }