diff --git a/pkgs/applications/misc/clight/default.nix b/pkgs/applications/misc/clight/default.nix
index 6ef2e886a190..e502cd6ccf3b 100644
--- a/pkgs/applications/misc/clight/default.nix
+++ b/pkgs/applications/misc/clight/default.nix
@@ -6,24 +6,21 @@
 
 stdenv.mkDerivation rec {
   pname = "clight";
-  version = "4.1";
+  version = "4.2";
 
   src = fetchFromGitHub {
     owner = "FedeDP";
     repo = "Clight";
     rev = version;
-    sha256 = "1j7va217g1k8lxl3lly13js8myf0shjc6knalq8q6lakc6j1mkxx";
+    sha256 = "sha256-NmfnE6ZWgG9erBmrFFIhutnB1t2Ix/6jo+EeXYVtehg=";
   };
 
-  # bash-completion.pc completionsdir=${bash-completion.out}
-  COMPLETIONS_DIR = "${placeholder "out"}/share/bash-completions/completions";
   # dbus-1.pc has datadir=/etc
   SESSION_BUS_DIR = "${placeholder "out"}/share/dbus-1/services";
 
   postPatch = ''
     sed -i "s@/usr@$out@" CMakeLists.txt
     sed -i "s@/etc@$out\0@" CMakeLists.txt
-    sed -i "s@pkg_get_variable(COMPLETIONS_DIR.*@set(COMPLETIONS_DIR $COMPLETIONS_DIR)@" CMakeLists.txt
     sed -i "s@pkg_get_variable(SESSION_BUS_DIR.*@set(SESSION_BUS_DIR $SESSION_BUS_DIR)@" CMakeLists.txt
   '';
 
@@ -46,6 +43,12 @@ stdenv.mkDerivation rec {
   ] ++ optional withGeoclue geoclue2
     ++ optional withUpower upower;
 
+  cmakeFlags = [
+    # bash-completion.pc completionsdir=${bash-completion.out}
+    "-DBASH_COMPLETIONS_DIR=${placeholder "out"}/share/bash-completions/completions"
+    "-DZSH_COMPLETIONS_DIR=${placeholder "out"}/share/zsh/site-functions"
+  ];
+
   meta = with lib; {
     description = "A C daemon that turns your webcam into a light sensor";
     homepage = "https://github.com/FedeDP/Clight";