diff --git a/ext/ZarrCoreExt.jl b/ext/ZarrCoreExt.jl
index 1d6e100..959b33c 100644
--- a/ext/ZarrCoreExt.jl
+++ b/ext/ZarrCoreExt.jl
@@ -94,7 +94,7 @@ end
 
 YAB.create_empty(::Type{ZarrDataset}, path, gatts=Dict(); format=2, kwargs...) =
   ZarrDataset(zgroup(ZarrCore.storefromstring(path, true)..., format; attrs=gatts))
-zarr_format(ds::ZarrDataset) = zarr_format(ds.g.metadata)
+zarr_format(ds::ZarrDataset) = Int(ds.g.zarr_format)
 
 
 
diff --git a/test/datasets.jl b/test/datasets.jl
index c5e4f44..45b2862 100644
--- a/test/datasets.jl
+++ b/test/datasets.jl
@@ -73,7 +73,7 @@ end
   h = get_var_handle(ds_loaded, "tas")
   @test h[:, :] == reshape(1:12, 3, 4)
   @test !YAXArrayBase.iscompressed(h)
-  @test !YAXArrayBase.iscompressed(zcreate(Float32, 3, 4, format=3))
+  @test !YAXArrayBase.iscompressed(zcreate(Float32, 3, 4; zarr_format=3))
   @test_throws "ZarrZip" to_dataset(tempname() * ".zarr.zip")
 end
 
@@ -81,8 +81,8 @@ using ZarrHTTP, ZarrBlosc, ZarrZip
 
 @testset "Zarr iscompressed" begin
   for format in (2, 3)
-    @test YAXArrayBase.iscompressed(zcreate(Float32, 3, 4; format))
-    @test !YAXArrayBase.iscompressed(zcreate(Float32, 3, 4; format, compressor=ZarrCore.NoCompressor()))
+    @test YAXArrayBase.iscompressed(zcreate(Float32, 3, 4; zarr_format=format))
+    @test !YAXArrayBase.iscompressed(zcreate(Float32, 3, 4; zarr_format=format, compressor=ZarrCore.NoCompressor()))
   end
 end
 
@@ -203,7 +203,7 @@ import JSON
     @test length(nodes) == 6
     for n in nodes
       j = JSON.parsefile(n)
-      @test j["format"] == 3
+      @test j["zarr_format"] == 3
       if j["node_type"] == "array"
         @test haskey(j, "dimension_names")
         @test !haskey(get(j, "attributes", Dict()), "_ARRAY_DIMENSIONS")