diff --git a/shell.nix b/shell.nix
index dd2950b29..34abf05ea 100644
--- a/shell.nix
+++ b/shell.nix
@@ -23,5 +23,6 @@ with import ./release-common.nix { inherit pkgs; };
       configureFlags+=" --prefix=$prefix"
       PKG_CONFIG_PATH=$prefix/lib/pkgconfig:$PKG_CONFIG_PATH
       PATH=$prefix/bin:$PATH
+      unset PYTHONPATH
     '';
 }