diff --git a/aniphallow.lua b/aniphallow.lua
index 5886675..a12a442 100644
--- a/aniphallow.lua
+++ b/aniphallow.lua
@@ -2656,7 +2656,13 @@ openMainDialog = function()
         text = "Analyze",
         visible = false,
         onclick = function()
-            if not S.sourceImage then return end
+            if not S.sourceImage then
+                refreshSource()
+            end
+            if not S.sourceImage then
+                app.alert("No source image. Open a sprite first.")
+                return
+            end
             local usedTileW = S.gbTileW
             local usedTileH = S.gbTileH
             if S.gbAnalyzeMode == "tile" then