diff --git a/tests/test_v3.py b/tests/test_v3.py
index 5579830..e8e8430 100644
--- a/tests/test_v3.py
+++ b/tests/test_v3.py
@@ -63,7 +63,7 @@ def test_sharding(
                 [
                     codecs.transpose_codec("F"),
                     codecs.bytes_codec(),
-                    codecs.blosc_codec(typesize=data.dtype.itemsize, cname="lz4"),
+                    codecs.blosc_codec(cname="lz4"),
                 ],
                 index_location=index_location,
             )
@@ -516,7 +516,7 @@ def test_open_sharding(store: Store):
                 [
                     codecs.transpose_codec("F"),
                     codecs.bytes_codec(),
-                    codecs.blosc_codec(typesize=4),
+                    codecs.blosc_codec(),
                 ],
             )
         ],
@@ -675,7 +675,7 @@ def test_write_partial_sharded_chunks(store: Store):
                 chunk_shape=(10, 10),
                 codecs=[
                     codecs.bytes_codec(),
-                    codecs.blosc_codec(typesize=data.dtype.itemsize),
+                    codecs.blosc_codec(),
                 ],
             )
         ],
diff --git a/zarrita/codecs.py b/zarrita/codecs.py
index 29d2f54..fb8f271 100644
--- a/zarrita/codecs.py
+++ b/zarrita/codecs.py
@@ -545,7 +545,7 @@ def compute_encoded_size(self, input_byte_length: int) -> int:
 
 
 def blosc_codec(
-    typesize: int,
+    typesize: int = 0,
     cname: Literal["lz4", "lz4hc", "blosclz", "zstd", "snappy", "zlib"] = "zstd",
     clevel: int = 5,
     shuffle: Literal["noshuffle", "shuffle", "bitshuffle"] = "noshuffle",
diff --git a/zarrita/metadata.py b/zarrita/metadata.py
index 34eacdd..60a270b 100644
--- a/zarrita/metadata.py
+++ b/zarrita/metadata.py
@@ -149,7 +149,7 @@ def encode_chunk_key(self, chunk_coords: ChunkCoords) -> str:
 
 @frozen
 class BloscCodecConfigurationMetadata:
-    typesize: int
+    typesize: int = 0
     cname: Literal["lz4", "lz4hc", "blosclz", "zstd", "snappy", "zlib"] = "zstd"
     clevel: int = 5
     shuffle: BloscShuffle = "noshuffle"