diff --git a/pkgs/tools/networking/mtr/default.nix b/pkgs/tools/networking/mtr/default.nix
index 8296bc479195..1257c167e768 100644
--- a/pkgs/tools/networking/mtr/default.nix
+++ b/pkgs/tools/networking/mtr/default.nix
@@ -1,17 +1,15 @@
 { stdenv, lib, fetchFromGitHub, autoreconfHook, pkg-config
 , libcap, ncurses
-, withGtk ? false, gtk3 ? null }:
-
-assert withGtk -> gtk3 != null;
+, withGtk ? false, gtk3 }:
 
 stdenv.mkDerivation rec {
   pname = "mtr${lib.optionalString withGtk "-gui"}";
   version = "0.94";
 
   src = fetchFromGitHub {
-    owner  = "traviscross";
-    repo   = "mtr";
-    rev    = "v${version}";
+    owner = "traviscross";
+    repo = "mtr";
+    rev = "v${version}";
     sha256 = "0wnz87cr2lcl74bj8qxq9xgai40az3pk9k0z893scyc8svd61xz6";
   };
 
@@ -38,9 +36,9 @@ stdenv.mkDerivation rec {
 
   meta = with lib; {
     description = "A network diagnostics tool";
-    homepage    = "https://www.bitwizard.nl/mtr/";
-    license     = licenses.gpl2;
+    homepage = "https://www.bitwizard.nl/mtr/";
+    license = licenses.gpl2;
     maintainers = with maintainers; [ koral orivej raskin globin ];
-    platforms   = platforms.unix;
+    platforms = platforms.unix;
   };
 }