diff --git a/boost/Jamroot b/boost/Jamroot
index 63dd757..200aa52 100644
--- a/boost/Jamroot
+++ b/boost/Jamroot
@@ -344,7 +344,7 @@ rule tag ( name : type ? : property-set )
         else
         {
             local result = [ common.format-name
-                <base> 
+                <base> <threading>
                 -$(BUILD_ID)
                 : $(name) : $(type) : $(property-set) ] ;
 
diff --git a/boost/tools/build/v2/tools/common.jam b/boost/tools/build/v2/tools/common.jam
index 20f52d5..60b3986 100644
--- a/boost/tools/build/v2/tools/common.jam
+++ b/boost/tools/build/v2/tools/common.jam
@@ -889,7 +889,8 @@ local rule threading-tag ( name : type ? : property-set )
 {
     local tag = ;
     local properties = [ $(property-set).raw ] ;
-    if <threading>multi in $(properties) { tag = mt ; }
+    if <threading>multi in $(properties) { tag = ; }
+    else { tag = st ; }
 
     return $(tag:J=) ;
 }