diff --git a/pkgs/by-name/cl/claude-code/package.nix b/pkgs/by-name/cl/claude-code/package.nix
index fb421ed233e3..b81187ca9982 100644
--- a/pkgs/by-name/cl/claude-code/package.nix
+++ b/pkgs/by-name/cl/claude-code/package.nix
@@ -28,9 +28,11 @@ buildNpmPackage rec {
 
   # `claude-code` tries to auto-update by default, this disables that functionality.
   # https://docs.anthropic.com/en/docs/agents-and-tools/claude-code/overview#environment-variables
+  # The DEV=true env var causes claude to crash with `TypeError: window.WebSocket is not a constructor`
   postInstall = ''
     wrapProgram $out/bin/claude \
-      --set DISABLE_AUTOUPDATER 1
+      --set DISABLE_AUTOUPDATER 1 \
+      --unset DEV
   '';
 
   passthru.updateScript = ./update.sh;