diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..2350c48
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+# Windows
+Thumbs.db
+ehthumbs.db
+Desktop.ini
diff --git a/adbreak/adbreak.html b/adbreak/adbreak.html
index b50f8a5..cb54293 100644
--- a/adbreak/adbreak.html
+++ b/adbreak/adbreak.html
@@ -196,6 +196,10 @@
 alert("Version number is: " + ver);
 
 var entry = offsets[ver];
+if (!entry) {
+  alert("This build is not in AdBreak's offset table: " + ver + "\nCheck firmware is 5.18.1-5.18.5 and that AdBreak supports your device.");
+  throw new Error("unsupported build");
+}
 var memcpy_got = entry.memcpy_got;
 var xml_got = entry.xml_got;
 var memcpy_offset = entry.memcpy_offset;
diff --git a/adbreak/guide.txt b/adbreak/guide.txt
index ca44015..529b0d4 100644
--- a/adbreak/guide.txt
+++ b/adbreak/guide.txt
@@ -29,7 +29,7 @@ Requirements:
 7. Download and extract "adbreak.zip", copy the contents to the ".assets" folder on your desktop.
 
 8. Replace the contents of all "details.html" files with the contents of "adbreak.html":
-  Windows: Double click on "replace.bat"
+  Windows: Double click on "replace.bat" (it searches from its own folder; you should see a list of each Replaced: path, or a message if none were found)
   Linux/Mac CLI: find . -name 'details.html' -exec cp adbreak.html {} \;
 
 9. Delete the original .assets folder on the Kindle and replace it with our modified copy.
diff --git a/adbreak/replace.bat b/adbreak/replace.bat
index a884250..788eda6 100644
--- a/adbreak/replace.bat
+++ b/adbreak/replace.bat
@@ -1,8 +1,25 @@
 @echo off
-setlocal
-for /r "." %%F in (details.html) do (
+setlocal EnableDelayedExpansion
+rem Always search from this script's folder. "Run as administrator" and some
+rem launch methods leave the current directory as System32, so for /r "."
+rem would find nothing and fail silently.
+set "_root=%~dp0"
+set /a _count=0
+for /r "%_root%" %%F in (details.html) do (
   if exist "%%~fF" (
-    copy /y "%~dp0adbreak.html" "%%~fF" >nul
+    copy /y "%_root%adbreak.html" "%%~fF" >nul
+    if not errorlevel 1 (
+      set /a _count+=1
+      echo Replaced: %%~fF
+    )
   )
 )
+if !_count! equ 0 (
+  echo No details.html files found under:
+  echo   %_root%
+  echo Put replace.bat next to adbreak.html inside your copied .assets tree, then run again.
+) else (
+  echo.
+  echo Done. Replaced !_count! file^(s^).
+)
 endlocal
\ No newline at end of file