diff --git a/test/data/data_slice.cpp b/test/data/data_slice.cpp
index 937b52a66b..9f07a46553 100644
--- a/test/data/data_slice.cpp
+++ b/test/data/data_slice.cpp
@@ -384,6 +384,8 @@ BOOST_AUTO_TEST_CASE(data_slice__construct__initializer__expected)
     // So this initializer requires explicit null termination.
     const data_slice slice7({ 'f', 'o', 'o', 'b', 'a', 'r', '\0' });
     BOOST_WARN(!slice7.empty());
+
+    // TODO: This is failing on clang/gcc.
     BOOST_WARN_EQUAL(slice7.size(), size);
     ////BOOST_WARN_EQUAL(slice7.encoded(), encoded);
 }