diff --git a/pkgs/applications/science/logic/ott/default.nix b/pkgs/applications/science/logic/ott/default.nix
index 48ad63eaa99..15a9fa5ccab 100644
--- a/pkgs/applications/science/logic/ott/default.nix
+++ b/pkgs/applications/science/logic/ott/default.nix
@@ -16,7 +16,13 @@ stdenv.mkDerivation rec {
 
   installTargets = "ott.install";
 
-  postInstall = "opaline -prefix $out";
+  postInstall = ''
+    opaline -prefix $out
+  ''
+  # There is `emacsPackages.ott-mode` for this now.
+  + ''
+    rm -r $out/share/emacs
+  '';
 
   meta = {
     description = "A tool for the working semanticist";