diff --git a/webknossos/webknossos/dataset/defaults.py b/webknossos/webknossos/dataset/defaults.py
index 649f8cbcc..3c742db1e 100644
--- a/webknossos/webknossos/dataset/defaults.py
+++ b/webknossos/webknossos/dataset/defaults.py
@@ -6,10 +6,12 @@
 DEFAULT_WKW_FILE_LEN = 32
 DEFAULT_CHUNK_SHAPE = Vec3Int.full(32)
 DEFAULT_DATA_FORMAT = (
-    DataFormat.WKW if not os.environ.get("DATA_FORMAT") == "zarr3" else DataFormat.Zarr3
+    DataFormat.WKW
+    if not os.environ.get("WK_DEFAULT_DATA_FORMAT") == "zarr3"
+    else DataFormat.Zarr3
 )
-DEFAULT_CHUNKS_PER_SHARD = (
-    Vec3Int.full(32) if DEFAULT_DATA_FORMAT == DataFormat.WKW else Vec3Int.full(16)
+DEFAULT_CHUNKS_PER_SHARD = Vec3Int.full(
+    int(os.environ.get("WK_DEFAULT_CHUNKS_PER_SHARD", 32))
 )
 DEFAULT_CHUNKS_PER_SHARD_ZARR = Vec3Int.full(1)
 DEFAULT_CHUNKS_PER_SHARD_FROM_IMAGES = Vec3Int(128, 128, 1)