diff --git a/lib/sources.nix b/lib/sources.nix
index 8f312a9db5c4..0ec4c020e545 100644
--- a/lib/sources.nix
+++ b/lib/sources.nix
@@ -17,6 +17,8 @@ rec {
     (type == "directory" && (baseName == ".git" || baseName == ".svn" || baseName == "CVS" || baseName == ".hg")) ||
     # Filter out backup files.
     lib.hasSuffix "~" baseName ||
+    builtins.match "^.*\.sw[a-z]$" baseName != null ||
+
     # Filter out generates files.
     lib.hasSuffix ".o" baseName ||
     lib.hasSuffix ".so" baseName ||
diff --git a/nixos/lib/make-disk-image.nix b/nixos/lib/make-disk-image.nix
index 9c91bf392251..d4b2e338c3ef 100644
--- a/nixos/lib/make-disk-image.nix
+++ b/nixos/lib/make-disk-image.nix
@@ -45,19 +45,7 @@ let
     raw   = "img";
   };
 
-  # Copied from https://github.com/NixOS/nixpkgs/blob/master/nixos/modules/installer/cd-dvd/channel.nix
-  # TODO: factor out more cleanly
-
-  # Do not include these things:
-  #   - The '.git' directory
-  #   - Result symlinks from nix-build ('result', 'result-2', 'result-bin', ...)
-  #   - VIM/Emacs swap/backup files ('.swp', '.swo', '.foo.swp', 'foo~', ...)
-  filterFn = path: type: let basename = baseNameOf (toString path); in
-    if type == "directory" then basename != ".git"
-    else if type == "symlink" then builtins.match "^result(|-.*)$" basename == null
-    else builtins.match "^((|\..*)\.sw[a-z]|.*~)$" basename == null;
-
-  nixpkgs = builtins.filterSource filterFn pkgs.path;
+  nixpkgs = lib.cleanSource pkgs.path;
 
   channelSources = pkgs.runCommand "nixos-${config.system.nixosVersion}" {} ''
     mkdir -p $out
diff --git a/nixos/modules/installer/cd-dvd/channel.nix b/nixos/modules/installer/cd-dvd/channel.nix
index 663ff24c81f1..ddb00f174d1a 100644
--- a/nixos/modules/installer/cd-dvd/channel.nix
+++ b/nixos/modules/installer/cd-dvd/channel.nix
@@ -6,16 +6,7 @@
 with lib;
 
 let
-  # Do not include these things:
-  #   - The '.git' directory
-  #   - Result symlinks from nix-build ('result', 'result-2', 'result-bin', ...)
-  #   - VIM/Emacs swap/backup files ('.swp', '.swo', '.foo.swp', 'foo~', ...)
-  filterFn = path: type: let basename = baseNameOf (toString path); in
-    if type == "directory" then basename != ".git"
-    else if type == "symlink" then builtins.match "^result(|-.*)$" basename == null
-    else builtins.match "^((|\..*)\.sw[a-z]|.*~)$" basename == null;
-
-  nixpkgs = builtins.filterSource filterFn pkgs.path;
+  nixpkgs = lib.cleanSource pkgs.path;
 
   # We need a copy of the Nix expressions for Nixpkgs and NixOS on the
   # CD.  These are installed into the "nixos" channel of the root