diff --git a/parse.y b/parse.y
index 590bd44..31d094d 100644
--- a/parse.y
+++ b/parse.y
@@ -438,6 +438,9 @@ yylex(void)
 			} else if (c == quotec) {
 				*p = '\0';
 				break;
+			} else if (c == '\0') {
+				yyerror("syntax error");
+				return (findeol());
 			}
 			if (p + 1 >= buf + sizeof(buf) - 1) {
 				yyerror("string too long");