diff --git a/node/Topology.hpp b/node/Topology.hpp
index f48a89b2f..f7804c293 100644
--- a/node/Topology.hpp
+++ b/node/Topology.hpp
@@ -237,7 +237,7 @@ public:
 		while (i.next(a,p)) {
 #ifdef ZT_TRACE
 			if (!(*p)) {
-				fprintf(stderr,"eachPeer() caught NULL peer for %s",a->toString().c_str());
+				fprintf(stderr,"FATAL BUG: eachPeer() caught NULL peer for %s -- peer pointers in Topology should NEVER be NULL",a->toString().c_str());
 				abort();
 			}
 #endif