diff --git a/luaparser/builder.py b/luaparser/builder.py
index 4d94cfc..4d90132 100644
--- a/luaparser/builder.py
+++ b/luaparser/builder.py
@@ -681,9 +681,11 @@ def visitString(self, ctx: LuaParser.StringContext):
             lua_str = lua_str[1:-1]
             delimiter = StringDelimiter.SINGLE_QUOTE
         # double square brackets notation:
-        elif m := LUA_DOUBLE_SQUARE_RE.match(lua_str):
-            lua_str = m.group("body")
-            delimiter = StringDelimiter.DOUBLE_SQUARE
+        else:
+            m = LUA_DOUBLE_SQUARE_RE.match(lua_str)
+            if m:
+                lua_str = m.group("body")
+                delimiter = StringDelimiter.DOUBLE_SQUARE
 
         if delimiter == StringDelimiter.DOUBLE_QUOTE or delimiter == StringDelimiter.SINGLE_QUOTE:
             unescaped_str = unescape_lua_string(lua_str)