diff --git a/server.go b/server.go
index 48c04ff..dd86427 100644
--- a/server.go
+++ b/server.go
@@ -274,7 +274,12 @@
 				grpclog.Println("grpc: Server.Serve failed to create ServerTransport: ", err)
 				return
 			}
+			defer st.Close()
 			s.mu.Lock()
+			if s.conns == nil {
+				s.mu.Unlock()
+				return
+			}
 			s.conns[st] = true
 			s.mu.Unlock()
 			var wg sync.WaitGroup