diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
index 98adc96..f77271a 100644
--- a/test/Jamfile.v2
+++ b/test/Jamfile.v2
@@ -8,6 +8,7 @@ import testing ;
 project hash-tests
     : requirements
         <toolset>gcc:<define>_GLIBCXX_DEBUG
+        <toolset>gcc:<cxxflags>-Wsign-promo
     ;
 
 test-suite functional/hash