diff --git a/nix/pkgs/ec-cli.nix b/nix/pkgs/ec-cli.nix
index df5bd32..f8ce106 100644
--- a/nix/pkgs/ec-cli.nix
+++ b/nix/pkgs/ec-cli.nix
@@ -22,6 +22,10 @@ rustPlatform.buildRustPackage {
 
   cargoLock = {
     lockFile = ../../Cargo.lock;
+    outputHashes = {
+      # Filled iteratively when git dependencies change.
+      "moq-catalog-0.2.2" = "sha256-df9KXVBRiNewDJ7ZgGBja81PPnk8vC9TA0bDIG0892o=";
+    };
   };
 
   cargoBuildFlags = [ "-p" "ec-cli" ];