diff --git a/stead/snapshot.lua b/stead/snapshots.lua
similarity index 92%
rename from stead/snapshot.lua
rename to stead/snapshots.lua
index e6573b7..882f178 100644
--- a/stead/snapshot.lua
+++ b/stead/snapshots.lua
@@ -27,6 +27,11 @@ function make_snapshot(nr)
 	game._snapshots[nr] = h.txt;
 end
 
+function isSnapshot(nr)
+	if not tonumber(nr) then nr = 0 end
+	return (game._snapshots[nr] ~= nil)
+end
+
 function restore_snapshot(nr)
 	if not tonumber(nr) then nr = 0 end
 	local ss = game._snapshots