diff --git a/compacting-storage.lua b/compacting-storage.lua
index 0c0e604..ccb983c 100644
--- a/compacting-storage.lua
+++ b/compacting-storage.lua
@@ -133,19 +133,18 @@ function should_fill (type, counts)
         end
         if fill_src ~= nil and fill_dest ~= nil then break end
     end
-    local amount_to_use = do
-        local ratio = AMOUNT_USED / AMOUNT_RETURNED
-        local amount_needed_src = nil
-        if fill_src == "block" then
-            amount_needed_src = amount_needed / ratio
-        else
-            amount_needed_src = amount_needed * ratio
-        end
-        if amount_needed_src < amount_spare then
-            return amount_needed_src
-        else
-            return amount_spare
-        end
+    local amount_to_use = nil
+    local ratio = AMOUNT_USED / AMOUNT_RETURNED
+    local amount_needed_src = nil
+    if fill_src == "block" then
+        amount_needed_src = amount_needed / ratio
+    else
+        amount_needed_src = amount_needed * ratio
+    end
+    if amount_needed_src < amount_spare then
+        amount_to_use = amount_needed_src
+    else
+        amount_to_use = amount_spare
     end
     return fill_dest, fill_src, amount_to_use
 end