diff --git a/src/emacs.c b/src/emacs.c
index 6c7773770d7..d67c97a5f6e 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -1163,6 +1163,13 @@ main (argc, argv
 #if defined (USG5) && defined (INTERRUPT_INPUT)
       setpgrp ();
 #endif
+#endif
+#if defined (HAVE_GTK_AND_PTHREAD) && !defined (SYSTEM_MALLOC) && !defined (DOUG_LEA_MALLOC)
+      {
+	extern void malloc_enable_thread P_ ((void));
+
+	malloc_enable_thread ();
+      }
 #endif
     }