diff --git a/README.md b/README.md
index c33dbd0..a0fe609 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,5 @@
 # ZarrDatasets
 
-[![Build Status](https://github.com/JuliaGeo/ZarrDatasets.jl/actions/workflows/CI.yml/badge.svg?branch=main)](https://github.com/JuliaGeo/ZarrDatasets.jl/actions/workflows/CI.yml?query=branch%3Amain)
 [![Build Status](https://github.com/JuliaGeo/ZarrDatasets.jl/workflows/CI/badge.svg)](https://github.com/JuliaGeo/ZarrDatasets.jl/actions)
 [![codecov.io](http://codecov.io/github/JuliaGeo/ZarrDatasets.jl/coverage.svg?branch=main)](http://app.codecov.io/github/JuliaGeo/ZarrDatasets.jl?branch=main)
 [![documentation dev](https://img.shields.io/badge/docs-dev-blue.svg)](https://juliageo.github.io/ZarrDatasets.jl/dev/)
@@ -9,7 +8,7 @@
 ZarrDatasets.jl is a julia package to read [Zarr](https://zarr.dev/) datasets using the native julia implementation [Zarr.jl](https://github.com/JuliaIO/Zarr.jl)
 using the [CommonDataModel.jl](https://github.com/JuliaGeo/CommonDataModel.jl) interface.
 
-In the following example data from [Copernicus marine service](https://marine.copernicus.eu/) are loaded using `ZarrDatasets` and a subset
+In the following example, data from [Copernicus Marine Service](https://marine.copernicus.eu/) is loaded using `ZarrDatasets` and a subset
 is saved as a NetCDF file:
 
 
diff --git a/src/dataset.jl b/src/dataset.jl
index 04bdebd..4396595 100644
--- a/src/dataset.jl
+++ b/src/dataset.jl
@@ -57,7 +57,7 @@ CDM.group(ds::ZarrDataset,name::SymbolOrString) = ZarrDataset(ds.zgroup.groups,S
 
 
 CDM.parentdataset(ds::ZarrDataset) = ds.parentdataset
-CDM.iswritable(ds::ZarrDataset) = true
+CDM.iswritable(ds::ZarrDataset) = false
 CDM.maskingvalue(ds::ZarrDataset) = ds.maskingvalue
 
 
diff --git a/test/Project.toml b/test/Project.toml
index 9e60b1e..5c95be8 100644
--- a/test/Project.toml
+++ b/test/Project.toml
@@ -1,8 +1,9 @@
 [deps]
+CommonDataModel = "1fbeeb36-5f17-413c-809b-666fb144f157"
 Dates = "ade2ca70-3891-5945-98fb-dc099432e06a"
 NCDatasets = "85f8d34a-cbdd-5861-8df4-14fed0d494ab"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [compat]
-julia = "1"
 NCDatasets = "0.14"
+julia = "1"
diff --git a/test/runtests.jl b/test/runtests.jl
index a6d901d..79f2631 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -2,6 +2,7 @@ using Dates
 using NCDatasets
 using Test
 using ZarrDatasets
+using CommonDataModel: iswritable, attribnames, parentdataset
 
 @testset "ZarrDatasets.jl" begin
     #fname = "/tmp/foo.zarr"
@@ -44,6 +45,15 @@ using ZarrDatasets
         @test ds2.attrib[attribname] == attribval
     end
 
+    io = IOBuffer()
+    show(io,ds)
+    str = String(take!(io))
+    @test occursin("title",str)
+
+    @test !iswritable(ds)
+    @test "title" in attribnames(ds)
+    @test isnothing(parentdataset(ds))
+
     close(ds)
     close(ds2)
 end