diff --git a/pkgs/tools/networking/p2p/tahoe-lafs/default.nix b/pkgs/tools/networking/p2p/tahoe-lafs/default.nix
index 3e9d1f9f5f7..97bf456dbbd 100644
--- a/pkgs/tools/networking/p2p/tahoe-lafs/default.nix
+++ b/pkgs/tools/networking/p2p/tahoe-lafs/default.nix
@@ -50,8 +50,6 @@ pythonPackages.buildPythonApplication rec {
 
   nativeBuildInputs = with pythonPackages; [ sphinx texinfo ];
 
-  buildInputs = with pythonPackages; [ unzip numpy mock ];
-
   # The `backup' command requires `sqlite3'.
   propagatedBuildInputs = with pythonPackages; [
     twisted foolscap nevow simplejson zfec pycryptopp darcsver
@@ -59,7 +57,7 @@ pythonPackages.buildPythonApplication rec {
     service-identity pyyaml magic-wormhole treq
   ];
 
-  checkInputs = with pythonPackages; [ hypothesis twisted ];
+  checkInputs = with pythonPackages; [ mock hypothesis twisted ];
 
   # Install the documentation.
   postInstall = ''