diff --git a/src/Biblys/Isbn/groups-array.php b/src/Biblys/Isbn/groups-array.php
index 98c246f..7d0c38f 100644
--- a/src/Biblys/Isbn/groups-array.php
+++ b/src/Biblys/Isbn/groups-array.php
@@ -474,8 +474,8 @@
     '978-69990' => ['Zambia registration group', [
         ['0000000', '4999999', 0],
         ['5000000', '5099999', 2],
-        ['5100000', '9969999', 0],
-        ['9970000', '9999999', 3],
+        ['5100000', '9939999', 0],
+        ['9940000', '9999999', 3],
     ]],
     '978-7' => ['China, People\'s Republic', [
         ['0000000', '0999999', 2],