diff --git a/libguile/root.h b/libguile/root.h
index 370563dad..3240d5907 100644
--- a/libguile/root.h
+++ b/libguile/root.h
@@ -66,7 +66,12 @@
 #define scm_object_whash scm_sys_protects[12]
 #define scm_permobjs scm_sys_protects[13]
 #define scm_asyncs scm_sys_protects[14]
+#ifdef DEBUG_EXTENSIONS
+#define scm_source_whash scm_sys_protects[15]
+#define SCM_NUM_PROTECTS 16
+#else
 #define SCM_NUM_PROTECTS 15
+#endif
 
 extern SCM scm_sys_protects[];