diff --git a/quarry/net/auth.py b/quarry/net/auth.py
index 169e8a5..0e38f34 100644
--- a/quarry/net/auth.py
+++ b/quarry/net/auth.py
@@ -90,12 +90,21 @@ def _callback(data):
         d1.addCallbacks(_callback, d0.errback)
         return d0
 
-    @defer.inlineCallbacks
     def use_signing(self):
+        d0 = defer.Deferred()
+
+        def _callback(data):
+            self.certificates = data
+            self.enable_signing = True
+            d0.callback(self)
+
         if not self.certificates or self.certificates.is_expired():
-            self.certificates = yield self._get_certificates()
-        self.enable_signing = True
-        return self.certificates
+            d1 = self._get_certificates()
+            d1.addCallbacks(_callback, d0.errback)
+        else:
+            self.enable_signing = True
+            d0.callback(self.certificates)
+        return d0
 
     def refresh(self):
         d0 = defer.Deferred()