diff --git a/buildbot/status/web/waterfall.py b/buildbot/status/web/waterfall.py
index 3b061d2f878..4d34deb08a4 100644
--- a/buildbot/status/web/waterfall.py
+++ b/buildbot/status/web/waterfall.py
@@ -584,7 +584,7 @@ def with_args(req, remove_args=[], new_args=[], new_path=None):
                     newargs[k].append(v)
                 else:
                     newargs[k] = [v]
-            newquery = "&".join(["%s=%s" % (k, v)
+            newquery = "&".join(["%s=%s" % (k, urllib.quote(v))
                                  for k in newargs
                                  for v in newargs[k]
                                  ])