diff --git a/libasn1fix/check_fixer.c b/libasn1fix/check_fixer.c
index 21c5b12..7129a56 100644
--- a/libasn1fix/check_fixer.c
+++ b/libasn1fix/check_fixer.c
@@ -246,7 +246,7 @@
 			"CHECKER: Unsupported value type of \"%s\": "
 			"%d at line %d of %s\n",
 			check_expr->Identifier,
-			value?value->type:-1,
+			value?(signed)value->type:-1,
 			expr->_lineno,
 			mod->source_file_name
 		);