diff --git a/webservice/components/request_adapter.py b/webservice/components/request_adapter.py
index 4d7d00cb..4356bcf2 100644
--- a/webservice/components/request_adapter.py
+++ b/webservice/components/request_adapter.py
@@ -65,8 +65,14 @@ def _get_headers_for_api_key(self, **kw):
 
     def _get_url(self, url=None, url_params=None, **kwargs):
         if not url:
-            # TODO: if url is given, we should validate the domain
-            # to avoid abusing a webservice backend for different calls.
             url = self.collection.url
+        elif not url.startswith(self.collection.url):
+            if not url.startswith("http"):
+                url = self.collection.url + url
+            else:
+                # TODO: if url is given, we should validate the domain
+                # to avoid abusing a webservice backend for different calls.
+                pass
+
         url_params = url_params or kwargs
         return url.format(**url_params)
diff --git a/webservice/tests/test_webservice.py b/webservice/tests/test_webservice.py
index aee0ca54..c80c1df7 100644
--- a/webservice/tests/test_webservice.py
+++ b/webservice/tests/test_webservice.py
@@ -88,6 +88,17 @@ def test_web_service_get(self):
             responses.calls[0].request.headers["Content-Type"], "application/xml"
         )
 
+    @responses.activate
+    def test_web_service_get_url_compine(self):
+        endpoint = "api/test"
+        responses.add(responses.GET, self.url + endpoint, body="{}")
+        result = self.webservice.call("get", url="api/test")
+        self.assertEqual(result, b"{}")
+        self.assertEqual(len(responses.calls), 1)
+        self.assertEqual(
+            responses.calls[0].request.headers["Content-Type"], "application/xml"
+        )
+
     @responses.activate
     def test_web_service_post(self):
         responses.add(responses.POST, self.url, body="{}")