1 files changed, 4 insertions, 0 deletions
diff --git a/parse.y b/parse.y
index d7ed5b5f58..b1147fc97d 100644
--- a/parse.y
+++ b/parse.y
@@ -3528,6 +3528,10 @@ yylex()
 	    }
 	    else {
 		term = nextc();
+		if (ISALNUM(term) || ismbchar(term)) {
+		    yyerror("unknown type of %string");
+		    return 0;
+		}
 	    }
 	    if (c == -1 || term == -1) {
 		rb_compile_error("unterminated quoted string meets end of file");