diff --git a/README.md b/README.md
index e86c5f9..7295929 100644
--- a/README.md
+++ b/README.md
@@ -92,6 +92,11 @@ or:
 
 [Formulae](https://github.com/Homebrew/homebrew-core/blob/master/Formula/exa.rb)
 
+### Nix
+
+`exa` is also installable through [the derivation](https://github.com/NixOS/nixpkgs/blob/master/pkgs/tools/misc/exa/default.nix) using the [nix package manager](https://nixos.org/nix/) by running:
+
+    nix-env -i exa
 
 ## Testing with Vagrant
 
diff --git a/src/info/filetype.rs b/src/info/filetype.rs
index e1d3b2d..5d5378f 100644
--- a/src/info/filetype.rs
+++ b/src/info/filetype.rs
@@ -37,7 +37,7 @@ impl FileExtensions {
 
     fn is_video(&self, file: &File) -> bool {
         file.extension_is_one_of( &[
-            "avi", "flv", "m2v", "mkv", "mov", "mp4", "mpeg",
+            "avi", "flv", "m2v", "m4v", "mkv", "mov", "mp4", "mpeg",
             "mpg", "ogm", "ogv", "vob", "wmv", "webm", "m2ts",
         ])
     }