diff --git a/requires/testing.txt b/requires/testing.txt
index 1727c9f..82186ae 100644
--- a/requires/testing.txt
+++ b/requires/testing.txt
@@ -1,6 +1,6 @@
 coverage==4.5.4
 codecov==2.0.15
-flake8==3.7.8
+flake8==3.7.9
 flake8-comprehensions==2.2.0
 flake8-deprecated==1.3
 flake8-html==0.4.0
diff --git a/sprockets/mixins/http/__init__.py b/sprockets/mixins/http/__init__.py
index 7dcb6e2..7f4de97 100644
--- a/sprockets/mixins/http/__init__.py
+++ b/sprockets/mixins/http/__init__.py
@@ -360,9 +360,8 @@ class HTTPClientMixin:
 
         # Fail hard if someone is doing something wrong
         if 'raise_error' in kwargs:
-            raise RuntimeError(
-                self.__class__.__name__ + '.http_fetch called with ' +
-                'raise_error')
+            raise RuntimeError(self.__class__.__name__ + '.http_fetch '
+                               'called with raise_error')
 
         for attempt in range(0, max_http_attempts):
             LOGGER.debug('%s %s (Attempt %i of %i) %r',