diff --git a/spec/nginx_spec.moon b/spec/nginx_spec.moon
index dfd8403..a5ef9d8 100644
--- a/spec/nginx_spec.moon
+++ b/spec/nginx_spec.moon
@@ -104,6 +104,10 @@ describe "https://miti.sh/posts/", ->
 
 describe "https://miti.sh/posts", ->
   it "sends /posts/index.html", ->
+    with require "sitegen.path"
+      assert .exists("html/posts/index.html"),
+        "missing html/posts/index.html (try `make build file=blog.html`)"
+
     request = req "https://miti.sh/posts"
     assert.same request\statusCode!, 200
     assert.same request\statusMessage!, "OK"