diff --git a/src/portableML/poly/ConcIsaLib.sml b/src/portableML/poly/ConcIsaLib.sml
index 992c7c745d..d53c0c2a47 100644
--- a/src/portableML/poly/ConcIsaLib.sml
+++ b/src/portableML/poly/ConcIsaLib.sml
@@ -2,4 +2,5 @@ structure Mutex = Thread.Mutex;
 structure ConditionVar = Thread.ConditionVar;
 exception Thread = Thread.Thread
 
+structure PolyThread = Thread;
 structure Thread = Thread.Thread;