diff --git a/core/string/ustring.cpp b/core/string/ustring.cpp
index 8d6da31cf3..25c21486d6 100644
--- a/core/string/ustring.cpp
+++ b/core/string/ustring.cpp
@@ -4420,7 +4420,7 @@ String String::property_name_encode() const {
 	// as well as '"', '=' or ' ' (32)
 	const char32_t *cstr = get_data();
 	for (int i = 0; cstr[i]; i++) {
-		if (cstr[i] == '=' || cstr[i] == '"' || cstr[i] < 33 || cstr[i] > 126) {
+		if (cstr[i] == '=' || cstr[i] == '"' || cstr[i] == ';' || cstr[i] == '[' || cstr[i] == ']' || cstr[i] < 33 || cstr[i] > 126) {
 			return "\"" + c_escape_multiline() + "\"";
 		}
 	}