diff --git a/usr.bin/colldef/parse.y b/usr.bin/colldef/parse.y
index 052595516c68..2d47cf66227b 100644
--- a/usr.bin/colldef/parse.y
+++ b/usr.bin/colldef/parse.y
@@ -80,6 +80,8 @@ statment :
 	| order
 ;
 charmap : DEFN CHAR {
+	if (strlen($1) + 1 > CHARMAP_SYMBOL_LEN)
+		yyerror("Charmap symbol name '%s' is too long", $1);
 	strcpy(charmap_table[$2], $1);
 }
 ;