diff --git a/src/tools/msvc.jam b/src/tools/msvc.jam
index 667506f57..7eabfadf5 100644
--- a/src/tools/msvc.jam
+++ b/src/tools/msvc.jam
@@ -422,7 +422,7 @@ local rule configure-version-specific ( version : condition )
         
         # Improve floating-point accuracy. Otherwise, some of C++ Boost's
         # "math" tests will fail.
-        flags msvc.compile CFLAGS : /Op ;
+        flags msvc.compile CFLAGS $(condition) : /Op ;
     }
 }