diff --git a/hash/test/hash_custom_test.cpp b/hash/test/hash_custom_test.cpp
index b4bc5e7..d0cbcf0 100644
--- a/hash/test/hash_custom_test.cpp
+++ b/hash/test/hash_custom_test.cpp
@@ -30,7 +30,7 @@ namespace test
 namespace boost
 #endif
 {
-    std::size_t hash_value(custom x)
+    std::size_t hash_value(test::custom x)
     {
         return x.hash();
     }