diff --git a/obj/tools/btool.c b/obj/tools/btool.c
index 4846dff..f26f9be 100644
--- a/obj/tools/btool.c
+++ b/obj/tools/btool.c
@@ -122,7 +122,7 @@
 
 private varargs void print_map(mapping tmp,int cutoff)
 {
-	if (!mappingp(tmp))
+	if (!mappingp(tmp) || !sizeof(tmp))
 	{
 		this_interactive()->ReceiveMsg("Keine Daten vorhanden.\n");
 		return;