diff --git a/http/query_string.h b/http/query_string.h
index 10753ac..1cc68fb 100644
--- a/http/query_string.h
+++ b/http/query_string.h
@@ -326,6 +326,11 @@
 
     QueryString& operator=(const QueryString& qs)
     {
+        if (this == &qs)
+        {
+            return *this;
+        }
+
         url = qs.url;
         keyValuePairs.clear();
         for (auto p : qs.keyValuePairs)