diff --git a/owrx/controllers/__init__.py b/owrx/controllers/__init__.py
index c00eebd..8d227c3 100644
--- a/owrx/controllers/__init__.py
+++ b/owrx/controllers/__init__.py
@@ -16,7 +16,7 @@ class Controller(object):
         if last_modified is not None:
             headers["Last-Modified"] = last_modified.astimezone(tz=timezone.utc).strftime("%a, %d %b %Y %H:%M:%S GMT")
         if max_age is not None:
-            headers["Cache-Control"] = "max-age: {0}".format(max_age)
+            headers["Cache-Control"] = "max-age={0}".format(max_age)
         for key, value in headers.items():
             self.handler.send_header(key, value)
         self.handler.end_headers()