diff --git a/DigitalData.Core.Client/BaseHttpClientService.cs b/DigitalData.Core.Client/BaseHttpClientService.cs
index 08300ef..01a4ae6 100644
--- a/DigitalData.Core.Client/BaseHttpClientService.cs
+++ b/DigitalData.Core.Client/BaseHttpClientService.cs
@@ -47,17 +47,27 @@ namespace DigitalData.Core.Client
             // merge with default headers
             if(_headers is not null)
             {
-                var mergedHeaders = headers?.ToList() ?? new List<KeyValuePair<string, object>>();
-                mergedHeaders.AddRange(_headers);
-                headers = mergedHeaders;
+                if (headers is null)
+                    headers = _headers;
+                else
+                {
+                    var mergedHeaders = headers.ToList();
+                    mergedHeaders.AddRange(_headers);
+                    headers = mergedHeaders;
+                }
             }
 
             // Add default query parameters
             if(_queryParams is not null)
             {
-                var mergedQueryParams = queryParams?.ToList() ?? new List<KeyValuePair<string, object?>>();
-                mergedQueryParams.AddRange(_queryParams);
-                queryParams = mergedQueryParams;
+                if (queryParams is null)
+                    queryParams = _queryParams;
+                else
+                {
+                    var mergedQueryParams = queryParams.ToList();
+                    mergedQueryParams.AddRange(_queryParams);
+                    queryParams = mergedQueryParams;
+                }
             }
 
             // set default HTTP method as GET