diff --git a/src/usercmd.c b/src/usercmd.c
index 5db6f48..1a6fbee 100644
--- a/src/usercmd.c
+++ b/src/usercmd.c
@@ -57,6 +57,7 @@
     {EXPAND_USER_DEFINED, "custom"},
     {EXPAND_USER_LIST, "customlist"},
 #endif
+    {EXPAND_DIFF_BUFFERS, "diff_buffer"},
     {EXPAND_DIRECTORIES, "dir"},
     {EXPAND_ENV_VARS, "environment"},
     {EXPAND_EVENTS, "event"},