diff --git a/test/etap/140-attachment-comp.t b/test/etap/140-attachment-comp.t
index 130b09f..6f075ce 100755
--- a/test/etap/140-attachment-comp.t
+++ b/test/etap/140-attachment-comp.t
@@ -723,6 +723,6 @@
 
 test_text_data() ->
     {ok, Data} = file:read_file(
-        test_util:source_file("README")
+        test_util:source_file("README.rst")
     ),
     Data.