diff --git a/pkgs/by-name/mk/mkvtoolnix/package.nix b/pkgs/by-name/mk/mkvtoolnix/package.nix
index 229479be51de..2419af49df28 100644
--- a/pkgs/by-name/mk/mkvtoolnix/package.nix
+++ b/pkgs/by-name/mk/mkvtoolnix/package.nix
@@ -98,10 +98,13 @@ stdenv.mkDerivation (finalAttrs: {
   ++ optionals withGUI [ cmark ]
   ++ optionals stdenv.hostPlatform.isLinux [ qt6.qtwayland ];
 
-  # autoupdate is not needed but it silences a ton of pointless warnings
   postPatch = ''
+    # autoupdate is not needed but it silences a ton of pointless warnings
     patchShebangs . > /dev/null
     autoupdate configure.ac ac/*.m4
+
+    # fix unit tests with GUI disabled
+    sed -i '5i$gtest_apps.delete("gui") if !$build_mkvtoolnix_gui' rake.d/gtest.rb
   '';
 
   configureFlags = [