diff --git a/flake.nix b/flake.nix
index 8399201..9a6a011 100644
--- a/flake.nix
+++ b/flake.nix
@@ -199,6 +199,7 @@
               # Fancy REPL thing
               ocamlPackages.utop
               ocamlPackages.core
+              ocamlPackages.angstrom
             ];
 
             # Tools from packages