diff --git a/progress.go b/progress.go
index 4b21faf..27c45e9 100644
--- a/progress.go
+++ b/progress.go
@@ -356,6 +356,7 @@
 
 	if bs.middleware != nil {
 		bs.filler = bs.middleware(filler)
+		bs.middleware = nil
 	}
 
 	if s.popCompleted && !bs.noPop {