diff --git a/src/blupi.cxx b/src/blupi.cxx
index 8c294ad..01714eb 100644
--- a/src/blupi.cxx
+++ b/src/blupi.cxx
@@ -84,7 +84,7 @@ struct url_data {
   char *   buffer;
   size_t   size;
 };
-#endif
+#endif /* USE_CURL */
 
 template <typename Out>
 static void