diff --git a/flake.nix b/flake.nix
index d1e98df8..201d670e 100644
--- a/flake.nix
+++ b/flake.nix
@@ -61,7 +61,7 @@
               topiary-inplace = pkgs.writeShellApplication {
                 name = "topiary-inplace";
                 text = ''
-                  ${code.topiary-cli}/bin/topiary --in-place --input-files "$@";
+                  ${code.topiary-cli}/bin/topiary fmt "$@";
                 '';
               };
             in
diff --git a/playground.sh b/playground.sh
index a027b98b..40ed72bd 100755
--- a/playground.sh
+++ b/playground.sh
@@ -40,16 +40,10 @@ format() {
   local input="$2"
   local skip_idempotence="${3-1}"
 
-  local -a topiary_args=(
-    --query "${query}"
-    --input-files "${input}"
-  )
+  local -a topiary_args=(--query "${query}")
+  (( skip_idempotence )) && topiary_args+=(--skip-idempotence)
 
-  if (( skip_idempotence )); then
-    topiary_args+=(--skip-idempotence)
-  fi
-
-  cargo run --quiet -- "${topiary_args[@]}"
+  cargo run --quiet -- fmt "${topiary_args[@]}" < "${input}"
 }
 
 idempotency() {