diff --git a/src/keymap.h b/src/keymap.h
index d6dd5cb..47294f0 100644
--- a/src/keymap.h
+++ b/src/keymap.h
@@ -114,6 +114,9 @@
 #define KS_SGR_MOUSE		237
 #define KS_SGR_MOUSE_RELEASE	236
 
+/* Used for the GPM mouse. */
+#define KS_GPM_MOUSE		235
+
 /*
  * Filler used after KS_SPECIAL and others
  */