diff --git a/spdy/core/spdy_test_utils.h b/spdy/core/spdy_test_utils.h
index e2c3b47..ff08a50 100644
--- a/spdy/core/spdy_test_utils.h
+++ b/spdy/core/spdy_test_utils.h
@@ -19,7 +19,7 @@
 
 inline bool operator==(SpdyStringPiece x,
                        const SpdyHeaderBlock::ValueProxy& y) {
-  return x == y.as_string();
+  return y.operator==(x);
 }
 
 namespace test {