diff --git a/src/ASM/ASMs2D.C b/src/ASM/ASMs2D.C
index 32897490..49097c7b 100644
--- a/src/ASM/ASMs2D.C
+++ b/src/ASM/ASMs2D.C
@@ -736,6 +736,8 @@ bool ASMs2D::collapseEdge (int edge, int basis)
       return false;
     }
 
+  threadGroups.stripDir = edge <= 2 ? ThreadGroups::U : ThreadGroups::V;
+
   return true;
 }