diff --git a/pkgs/by-name/op/openmsx/package.nix b/pkgs/by-name/op/openmsx/package.nix
index 7167d5b86642..bf2722098390 100644
--- a/pkgs/by-name/op/openmsx/package.nix
+++ b/pkgs/by-name/op/openmsx/package.nix
@@ -14,6 +14,7 @@
   libpng,
   libtheora,
   libvorbis,
+  libX11,
   python3,
   tcl,
   zlib,
@@ -40,6 +41,7 @@ stdenv.mkDerivation (finalAttrs: {
     SDL2
     SDL2_image
     SDL2_ttf
+    libX11
     alsa-lib
     freetype
     glew