diff --git a/src/signal.cpp b/src/signal.cpp
--- a/src/signal.cpp
+++ b/src/signal.cpp
@@ -153,7 +153,7 @@ public:
 	{
 		if (this->IsFull()) {
 			overflowed = true;
-			DEBUG(misc, 0, "SignalSegment too complex. Set %s is full (maximum %d)", name, items);
+			Debug(misc, 0, "SignalSegment too complex. Set {} is full (maximum {})", name, items);
 			return false; // set is full
 		}