diff --git a/bin/mechanicaldiff.py b/bin/mechanicaldiff.py
index 2df8c9e..57c5cbf 100755
--- a/bin/mechanicaldiff.py
+++ b/bin/mechanicaldiff.py
@@ -118,7 +118,7 @@ def main() -> None:
 
     for section in sections:
         if not section["hunks"]:
-            output_lines.extend(section["header"])
+            left_out = True
             continue
 
         kept_hunks = []
diff --git a/test/mechanicaldiff.bats b/test/mechanicaldiff.bats
index 6a20d94..beb4853 100755
--- a/test/mechanicaldiff.bats
+++ b/test/mechanicaldiff.bats
@@ -30,7 +30,7 @@ setup() {
   assert_output ""
 }
 
-@test "keeps diff with only mode change" {
+@test "drops diff with only mode change" {
   printf "%s\n" "foo" >"$BATS_TEST_TMPDIR/old"
   printf "%s\n" "foo" >"$BATS_TEST_TMPDIR/new"
   chmod 0644 "$BATS_TEST_TMPDIR/old"
@@ -40,8 +40,8 @@ setup() {
     "$BATS_TEST_TMPDIR/new" || true)"
 
   run mechanicaldiff.py foo bar <<<"$diff_output"
-  assert_success
-  assert_output "$diff_output"
+  assert_failure
+  assert_output ""
 }
 
 @test "drops one hunk and keeps another" {