diff --git a/decor/decorator.go b/decor/decorator.go
index a3d04da..34b2837 100644
--- a/decor/decorator.go
+++ b/decor/decorator.go
@@ -156,6 +156,9 @@
 
 // Sync is implementation of Synchronizer interface.
 func (wc *WC) Sync() (chan int, bool) {
+	if (wc.C&DSyncWidth) != 0 && wc.wsync == nil {
+		panic(fmt.Sprintf("%T is not initialized", wc))
+	}
 	return wc.wsync, (wc.C & DSyncWidth) != 0
 }