diff --git a/tools/python/maps_generator/README.md b/tools/python/maps_generator/README.md
index d69dfd70f..34ab2240c 100644
--- a/tools/python/maps_generator/README.md
+++ b/tools/python/maps_generator/README.md
@@ -68,7 +68,7 @@ python -m maps_generator --countries="Macedonia" --skip="Coastline"
 
 It's possible to skip coastlines for countries that have a sea coast too, but the sea water will not be rendered in that case.
 
-Make sure that requested countries are contained in your planet dump file indeed. Filenames in `data/borders/` (without the `.poly` extension) represent all valid country names.
+Make sure that you specify country names that are actually contained in your pbf file, or you'll get errors in the next step. Check the filenames in the `data/borders/` folder (without the `.poly` extension) for a list of all valid country names. For example, New York City is in `US_New York_New_York` and all of England (minus Ireland, Scotland, and Wales) can be generated by specifying `UK_England_*`.
 
 To see other possible command-line options:
 ```sh