diff --git a/pkgs/tools/misc/diffoscope/default.nix b/pkgs/tools/misc/diffoscope/default.nix
index 6a9763666d3..4f0a9ba12c1 100644
--- a/pkgs/tools/misc/diffoscope/default.nix
+++ b/pkgs/tools/misc/diffoscope/default.nix
@@ -29,11 +29,13 @@ python3.pkgs.buildPythonApplication rec {
   # Still missing these tools: enjarify, otool & lipo (maybe OS X only), showttf
   # Also these libraries: python3-guestfs
   # FIXME: move xxd into a separate package so we don't have to pull in all of vim.
-  propagatedBuildInputs = (with python3.pkgs; [ debian libarchive-c python_magic tlsh rpm ]) ++
+  buildInputs =
     map lib.getBin ([ acl binutils bzip2 cbfstool cdrkit cpio diffutils e2fsprogs file gettext
       gzip libcaca poppler_utils sng sqlite squashfsTools unzip vim xz colordiff
     ] ++ lib.optionals enableBloat [ colord fpc ghc gnupg1 jdk mono pdftk ]);
 
+  pythonPath = with python3.pkgs; [ debian libarchive-c python_magic tlsh rpm ];
+
   doCheck = false; # Calls 'mknod' in squashfs tests, which needs root
 
   postInstall = ''