diff --git a/boost/boostcpp.jam b/boost/boostcpp.jam

index 257e70d..5afc6cc 100644

--- a/boost/boostcpp.jam

+++ b/boost/boostcpp.jam

@@ -136,7 +136,7 @@ rule tag ( name : type ? : property-set )

         else if $(layout) = system

         {

             result = [ common.format-name

-                <base>

+                <base> <threading>

                 -$(BUILD_ID)

                 : $(name) : $(type) : $(property-set) ] ;

         }

diff --git a/boost/tools/build/src/tools/common.jam b/boost/tools/build/src/tools/common.jam

index 8404feb..16a3fc7 100644

--- a/boost/tools/build/src/tools/common.jam

+++ b/boost/tools/build/src/tools/common.jam

@@ -907,7 +907,11 @@ local rule threading-tag ( name : type ? : property-set )

 {

     if <threading>multi in [ $(property-set).raw ]

     {

-        return mt ;

+        return ;

+    }

+    else

+    {

+        return st ;

     }

 }