diff --git a/libguile/libguile.h b/libguile/libguile.h
index 90e9d37f3..a2c63c203 100644
--- a/libguile/libguile.h
+++ b/libguile/libguile.h
@@ -118,6 +118,9 @@
 #include "libguile/version.h"
 #include "libguile/vports.h"
 #include "libguile/weaks.h"
+#ifdef USE_THREADS
+#include "libguile/../threads/threads.h"
+#endif