diff --git a/scripts/generatePmTilesExtracts.ts b/scripts/generatePmTilesExtracts.ts
index d72b96ae7a..152ce0f1c5 100644
--- a/scripts/generatePmTilesExtracts.ts
+++ b/scripts/generatePmTilesExtracts.ts
@@ -37,7 +37,7 @@ class GeneratePmTilesExtracts extends Script {
     }
 
     private* generateField(z: number, maxzoom?: number): Generator<Promise<void>> {
-        const boundary = 2 << z
+        const boundary = 2 << (z - 1)
         for (let x = 0; x < boundary; x++) {
             for (let y = 0; y < boundary; y++) {
                 yield this.generateArchive(z, x, y, maxzoom)