diff --git a/.gitignore b/.gitignore
index 6730149e0..8739f70ef 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,5 @@
 *.a
 *~
 *.so
+.envrc
+.direnv
diff --git a/shell.nix b/shell.nix
new file mode 100644
index 000000000..94d8a8634
--- /dev/null
+++ b/shell.nix
@@ -0,0 +1,15 @@
+# This is a nix-shell for use with the nix package manager.
+# If you have nix installed, you may simply run `nix-shell`
+# in this repo, and have all dependencies ready in the new shell.
+
+{ pkgs ? import <nixpkgs> {} }:
+pkgs.mkShell {
+  buildInputs = with pkgs;
+    [
+      graphicsmagick
+      libwebp
+      ffmpeg
+      pkg-config
+      python3
+    ];
+}
diff --git a/utils/.gitignore b/utils/.gitignore
index 264ccde73..6f5cc29f1 100644
--- a/utils/.gitignore
+++ b/utils/.gitignore
@@ -1,2 +1,3 @@
 led-image-viewer
 video-viewer
+text-scroller
diff --git a/utils/video-viewer.cc b/utils/video-viewer.cc
index 2b86e0bed..b89ee7ec0 100644
--- a/utils/video-viewer.cc
+++ b/utils/video-viewer.cc
@@ -292,7 +292,7 @@ int main(int argc, char *argv[]) {
       // Find the first video stream
       int videoStream = -1;
       AVCodecParameters *codec_parameters = NULL;
-      AVCodec *av_codec = NULL;
+      const AVCodec *av_codec = NULL;
       for (int i = 0; i < (int)format_context->nb_streams; ++i) {
         codec_parameters = format_context->streams[i]->codecpar;
         av_codec = avcodec_find_decoder(codec_parameters->codec_id);