diff --git a/README.md b/README.md
index 9771ff7..c940b6d 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 # Planetiler Basemap Profile
 
-This basemap profile is based on [OpenMapTiles](https://github.com/openmaptiles/openmaptiles) v3.12.2.
+This basemap profile is based on [OpenMapTiles](https://github.com/openmaptiles/openmaptiles) v3.13.
 See [README.md](../README.md) in the parent directory for instructions on how to run.
 
 ## Differences from OpenMapTiles
@@ -41,11 +41,17 @@ To run `Generate.java`, use [scripts/regenerate-openmaptiles.sh](../scripts/rege
 OpenMapTiles release tag:
 
 ```bash
-./scripts/regenerate-openmaptiles.sh v3.12.2
+./scripts/regenerate-openmaptiles.sh v3.13
 ```
 
 Then follow the instructions it prints for reformatting generated code.
 
+If you want to regenerate from a different repository than the default openmaptiles, you can specify the url like this:
+
+```bash
+./scripts/regenerate-openmaptiles.sh v3.13 https://raw.githubusercontent.com/openmaptiles/openmaptiles/
+```
+
 ## License and Attribution
 
 OpenMapTiles code is licensed under the BSD 3-Clause License, which appears at the top of any file ported from
diff --git a/src/main/java/com/onthegomap/planetiler/basemap/Generate.java b/src/main/java/com/onthegomap/planetiler/basemap/Generate.java
index 1ab032a..554ee32 100644
--- a/src/main/java/com/onthegomap/planetiler/basemap/Generate.java
+++ b/src/main/java/com/onthegomap/planetiler/basemap/Generate.java
@@ -128,8 +128,10 @@ public class Generate {
   public static void main(String[] args) throws IOException {
     Arguments arguments = Arguments.fromArgsOrConfigFile(args);
     PlanetilerConfig planetilerConfig = PlanetilerConfig.from(arguments);
-    String tag = arguments.getString("tag", "openmaptiles tag to use", "v3.12.2");
-    String base = "https://raw.githubusercontent.com/openmaptiles/openmaptiles/" + tag + "/";
+    String tag = arguments.getString("tag", "openmaptiles tag to use", "v3.13");
+    String baseUrl = arguments.getString("base-url", "the url used to download the openmaptiles.yml",
+      "https://raw.githubusercontent.com/openmaptiles/openmaptiles/");
+    String base = baseUrl + tag + "/";
 
     // start crawling from openmaptiles.yaml
     // then crawl schema from each layers/<layer>/<layer>.yaml file that it references