diff --git a/ci-tools/update-nixpkgs b/ci-tools/update-nixpkgs
index bdd0d2d2f8ec3f5bec16706817d264e13f9fb5a2..84d08432a628b3e5e9096b90baa72725f73a6871 100755
--- a/ci-tools/update-nixpkgs
+++ b/ci-tools/update-nixpkgs
@@ -1,5 +1,5 @@
 #!/usr/bin/env nix-shell
-#!nix-shell -i sh -p nixUnstable git openssh curl
+#!nix-shell -i bash -p nixUnstable git openssh curl
 
 # ^^
 # we get nixUnstable for the diff-closures command, mostly.