diff --git a/.gitignore b/.gitignore
index 02b4f83..90439c2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -26,3 +26,7 @@ node_modules/
 # Secrets
 .env
 .env.local
+
+# Sidecar fat JAR — build artifact copied in by `make uatu` before
+# `go build -tags withsidecar`. Never commit: it's ~130 MB.
+internal/sidecar/assets/sidecar-all.jar
diff --git a/internal/sidecar/assets/sidecar-all.jar b/internal/sidecar/assets/sidecar-all.jar
deleted file mode 100644
index dac0c12..0000000
--- a/internal/sidecar/assets/sidecar-all.jar
+++ /dev/null
@@ -1 +0,0 @@
-uatu-sidecar-placeholder
\ No newline at end of file