diff --git a/src/syntax.c b/src/syntax.c
index df351a3..7545165 100644
--- a/src/syntax.c
+++ b/src/syntax.c
@@ -10014,7 +10014,7 @@
     char_u	*end;
     int		id;
 #ifdef USER_HIGHLIGHT
-    char_u      userhl[10];
+    char_u      userhl[30];  // use 30 to avoid compiler warning
 # ifdef FEAT_STL_OPT
     int		id_S = -1;
     int		id_SNC = 0;