diff --git a/Project.toml b/Project.toml
index 6058003..51419a0 100644
--- a/Project.toml
+++ b/Project.toml
@@ -16,10 +16,4 @@ DataStructures = "0.17, 0.18"
 DiskArrays = "0.3.22, 0.4"
 JSON = "0.21"
 Zarr = "0.9.2"
-julia = "1"
-
-[extras]
-Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
-
-[targets]
-test = ["Test"]
+julia = "1.6"
diff --git a/src/dataset.jl b/src/dataset.jl
index c2f5ef6..c6881b5 100644
--- a/src/dataset.jl
+++ b/src/dataset.jl
@@ -137,7 +137,7 @@ function ZarrDataset(url::AbstractString,mode = "r";
         zg = zgroup(store, "",attrs = Dict(attrib))
         iswritable = true
     end
-    ZarrDataset(zg,parentdataset,dimensions,iswritable,maskingvalue)
+    ZarrDataset(parentdataset,zg,dimensions,iswritable,maskingvalue)
 end
 
 
diff --git a/src/types.jl b/src/types.jl
index fff77e3..21379c5 100644
--- a/src/types.jl
+++ b/src/types.jl
@@ -1,12 +1,12 @@
 
-struct ZarrVariable{T,N,TZA,TZG} <: CDM.AbstractVariable{T,N} where TZA  <: AbstractArray{T,N}
+struct ZarrVariable{T,N,TZA <: AbstractArray{T,N},TZG} <: CDM.AbstractVariable{T,N}
     zarray::TZA
     parentdataset::TZG
 end
 
-struct ZarrDataset{TZ,TP,Tmaskingvalue} <: CDM.AbstractDataset
+struct ZarrDataset{TDS <: Union{CDM.AbstractDataset,Nothing},Tmaskingvalue,TZ} <: CDM.AbstractDataset
+    parentdataset::TDS
     zgroup::TZ
-    parentdataset::TP
     dimensions::OrderedDict{Symbol,Int}
     iswritable::Bool
     maskingvalue::Tmaskingvalue
diff --git a/src/variable.jl b/src/variable.jl
index 81eed7d..fd61f29 100644
--- a/src/variable.jl
+++ b/src/variable.jl
@@ -1,8 +1,8 @@
 
-Base.getindex(v::ZarrVariable,ij...) = v.zarray[ij...]
+Base.getindex(v::ZarrVariable,ij::Union{Integer,Colon,AbstractVector{<:Integer}}...) = v.zarray[ij...]
 CDM.load!(v::ZarrVariable,buffer,ij...) = buffer .= view(v.zarray,ij...)
 
-function Base.setindex!(v::ZarrVariable,data,ij...)
+function Base.setindex!(v::ZarrVariable,data,ij::Union{Integer,Colon,AbstractVector{<:Integer}}...)
     v.zarray[ij...] = data
 end
 Base.size(v::ZarrVariable) = size(v.zarray)
diff --git a/test/Project.toml b/test/Project.toml
index efdf987..76756a4 100644
--- a/test/Project.toml
+++ b/test/Project.toml
@@ -1,4 +1,5 @@
 [deps]
+Aqua = "4c88cf16-eb10-579e-8560-4a9242c79595"
 CommonDataModel = "1fbeeb36-5f17-413c-809b-666fb144f157"
 Dates = "ade2ca70-3891-5945-98fb-dc099432e06a"
 DiskArrays = "3c3547ce-8d99-4f5e-a174-61eb10b00ae3"
@@ -6,5 +7,6 @@ NCDatasets = "85f8d34a-cbdd-5861-8df4-14fed0d494ab"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [compat]
+Aqua = "0.8"
 NCDatasets = "0.14"
 julia = "1"
diff --git a/test/runtests.jl b/test/runtests.jl
index 1f79678..63a6493 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -5,4 +5,5 @@ using ZarrDatasets
     include("test_cdm.jl")
     include("test_multifile.jl")
     include("test_write.jl")
+    include("test_aqua.jl")
 end
diff --git a/test/test_aqua.jl b/test/test_aqua.jl
new file mode 100644
index 0000000..29636c9
--- /dev/null
+++ b/test/test_aqua.jl
@@ -0,0 +1,4 @@
+using Aqua
+using ZarrDatasets
+
+Aqua.test_ambiguities(ZarrDatasets)