diff --git a/pkgs/tools/networking/p2p/tahoe-lafs/default.nix b/pkgs/tools/networking/p2p/tahoe-lafs/default.nix
index 97bf456dbbd9..1458ca65f924 100644
--- a/pkgs/tools/networking/p2p/tahoe-lafs/default.nix
+++ b/pkgs/tools/networking/p2p/tahoe-lafs/default.nix
@@ -54,7 +54,7 @@ pythonPackages.buildPythonApplication rec {
   propagatedBuildInputs = with pythonPackages; [
     twisted foolscap nevow simplejson zfec pycryptopp darcsver
     setuptoolsTrial setuptoolsDarcs pycrypto pyasn1 zope_interface
-    service-identity pyyaml magic-wormhole treq
+    service-identity pyyaml magic-wormhole treq characteristic
   ];
 
   checkInputs = with pythonPackages; [ mock hypothesis twisted ];