diff --git a/pkgs/by-name/sy/syncterm/package.nix b/pkgs/by-name/sy/syncterm/package.nix
index 8a8e27fc7a28..42673516194a 100644
--- a/pkgs/by-name/sy/syncterm/package.nix
+++ b/pkgs/by-name/sy/syncterm/package.nix
@@ -8,6 +8,7 @@
   autoPatchelfHook,
   ncurses,
   SDL2,
+  libX11,
   alsa-lib,
 }:
 
@@ -45,6 +46,7 @@ stdenv.mkDerivation rec {
     autoPatchelfHook
     pkg-config
     SDL2
+    libX11
     perl
     unzip
   ]; # SDL2 for `sdl2-config`.