diff --git a/firebase_admin/messaging.py b/firebase_admin/messaging.py
index e4e223091..217cf0a56 100644
--- a/firebase_admin/messaging.py
+++ b/firebase_admin/messaging.py
@@ -453,9 +453,12 @@ def _handle_iid_error(self, error):
         except ValueError:
             pass
 
-        # IID error response format: {"error": "some error message"}
-        msg = data.get('error')
-        if not msg:
+        # IID error response format: {"error": "ErrorCode"}
+        code = data.get('error')
+        msg = None
+        if code:
+            msg = 'Error while calling the IID service: {0}'.format(code)
+        else:
             msg = 'Unexpected HTTP response with status: {0}; body: {1}'.format(
                 error.response.status_code, error.response.content.decode())
 
diff --git a/tests/test_messaging.py b/tests/test_messaging.py
index 6e776cc5f..6333aad46 100644
--- a/tests/test_messaging.py
+++ b/tests/test_messaging.py
@@ -2286,7 +2286,7 @@ def test_subscribe_to_topic_error(self, status, exc_type):
             status=status, payload=self._DEFAULT_ERROR_RESPONSE)
         with pytest.raises(exc_type) as excinfo:
             messaging.subscribe_to_topic('foo', 'test-topic')
-        assert str(excinfo.value) == 'error_reason'
+        assert str(excinfo.value) == 'Error while calling the IID service: error_reason'
         assert len(recorder) == 1
         assert recorder[0].method == 'POST'
         assert recorder[0].url == self._get_url('iid/v1:batchAdd')
@@ -2318,7 +2318,7 @@ def test_unsubscribe_from_topic_error(self, status, exc_type):
             status=status, payload=self._DEFAULT_ERROR_RESPONSE)
         with pytest.raises(exc_type) as excinfo:
             messaging.unsubscribe_from_topic('foo', 'test-topic')
-        assert str(excinfo.value) == 'error_reason'
+        assert str(excinfo.value) == 'Error while calling the IID service: error_reason'
         assert len(recorder) == 1
         assert recorder[0].method == 'POST'
         assert recorder[0].url == self._get_url('iid/v1:batchRemove')