diff --git a/src/feature.h b/src/feature.h
index 8ebe94f..7bd73e7 100644
--- a/src/feature.h
+++ b/src/feature.h
@@ -379,6 +379,13 @@
 #endif
 
 /*
+ *			Insert mode completion with 'completefunc'.
+ */
+#if defined(FEAT_INS_EXPAND) && defined(FEAT_EVAL)
+# define FEAT_COMPL_FUNC
+#endif
+
+/*
  * +user_commands	Allow the user to define his own commands.
  */
 #ifdef FEAT_NORMAL