diff --git a/.gitignore b/.gitignore
index 428674ea..f3d2a7fb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,6 @@
 
 # direnv
 /.direnv
+
+# testing
+/tmp/empty
diff --git a/flake.nix b/flake.nix
index 1e7959bf..c9ba9e74 100644
--- a/flake.nix
+++ b/flake.nix
@@ -30,6 +30,7 @@
           pkgs.cargo-edit
           pkgs.cargo-machete
           pkgs.cargo-nextest
+          pkgs.cargo-watch
           pkgs.clippy
           pkgs.rust-analyzer
           pkgs.rustPlatform.rustcSrc
diff --git a/justfile b/justfile
index 958d23a6..424a497b 100644
--- a/justfile
+++ b/justfile
@@ -6,10 +6,11 @@ build:
 # re-build on code changes, and run the reference agent each time a build is
 # successful
 dev:
+  mkdir -p ./tmp/empty
   cargo watch \
     -x test \
     -x 'run --bin ndc_hub_example \
-    -- serve --configuration <(echo 'null') \
+    -- serve --configuration ./tmp/empty \
     --otlp-endpoint http://localhost:4317'
 
 format: