diff --git a/Project.toml b/Project.toml
index 9464bc08..6a6a51ab 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "MCMCDiagnosticTools"
 uuid = "be115224-59cd-429b-ad48-344e309966f0"
 authors = ["David Widmann"]
-version = "0.3.4"
+version = "0.3.5"
 
 [deps]
 AbstractFFTs = "621f4979-c628-5d54-868e-fcf4e3e8185c"
diff --git a/README.md b/README.md
index d94fe42c..9561bee1 100644
--- a/README.md
+++ b/README.md
@@ -5,6 +5,7 @@
 [![Build Status](https://github.com/TuringLang/MCMCDiagnosticTools.jl/workflows/CI/badge.svg?branch=main)](https://github.com/TuringLang/MCMCDiagnosticTools.jl/actions?query=workflow%3ACI+branch%3Amain)
 [![Coverage](https://codecov.io/gh/TuringLang/MCMCDiagnosticTools.jl/branch/main/graph/badge.svg)](https://codecov.io/gh/TuringLang/MCMCDiagnosticTools.jl)
 [![Coverage](https://coveralls.io/repos/github/TuringLang/MCMCDiagnosticTools.jl/badge.svg?branch=main)](https://coveralls.io/github/TuringLang/MCMCDiagnosticTools.jl?branch=main)
+[![Aqua QA](https://raw.githubusercontent.com/JuliaTesting/Aqua.jl/master/badge.svg)](https://github.com/JuliaTesting/Aqua.jl)
 [![Code Style: Blue](https://img.shields.io/badge/code%20style-blue-4495d1.svg)](https://github.com/invenia/BlueStyle)
 [![ColPrac: Contributor's Guide on Collaborative Practices for Community Packages](https://img.shields.io/badge/ColPrac-Contributor's%20Guide-blueviolet)](https://github.com/SciML/ColPrac)
 
diff --git a/src/rstar.jl b/src/rstar.jl
index 41de1233..9b16b299 100644
--- a/src/rstar.jl
+++ b/src/rstar.jl
@@ -211,10 +211,7 @@ julia> round(value; digits=2)
 Lambert, B., & Vehtari, A. (2020). ``R^*``: A robust MCMC convergence diagnostic with uncertainty using decision tree classifiers.
 """
 function rstar(rng::Random.AbstractRNG, classifier, x::AbstractArray; kwargs...)
-    return rstar(rng, classifier, _params_array(x); kwargs...)
-end
-function rstar(rng::Random.AbstractRNG, classifier, x::AbstractArray{<:Any,3}; kwargs...)
-    samples = reshape(x, :, size(x, 3))
+    samples = reshape(x, size(x, 1) * size(x, 2), :)
     chain_inds = repeat(axes(x, 2); inner=size(x, 1))
     return rstar(rng, classifier, samples, chain_inds; kwargs...)
 end
@@ -222,6 +219,12 @@ end
 function rstar(classifier, x, y::AbstractVector{Int}; kwargs...)
     return rstar(Random.default_rng(), classifier, x, y; kwargs...)
 end
+# Fix method ambiguity issue
+function rstar(rng::Random.AbstractRNG, classifier, x::AbstractVector{Int}; kwargs...)
+    samples = reshape(x, length(x), :)
+    chain_inds = ones(Int, length(x))
+    return rstar(rng, classifier, samples, chain_inds; kwargs...)
+end
 
 function rstar(classifier, x::AbstractArray; kwargs...)
     return rstar(Random.default_rng(), classifier, x; kwargs...)
diff --git a/test/Project.toml b/test/Project.toml
index e1909c9c..553ae630 100644
--- a/test/Project.toml
+++ b/test/Project.toml
@@ -1,4 +1,5 @@
 [deps]
+Aqua = "4c88cf16-eb10-579e-8560-4a9242c79595"
 Distributions = "31c24e10-a181-5473-b8eb-7969acd0382f"
 DynamicHMC = "bbc10e6e-7c05-544b-b16e-64fede858acb"
 EvoTrees = "f6006082-12f8-11e9-0c9c-0d5d367ab1e5"
@@ -19,6 +20,7 @@ Tables = "bd369af6-aec1-5ad0-b16a-f7cc5008161c"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [compat]
+Aqua = "0.6.5"
 Distributions = "0.25"
 DynamicHMC = "3"
 EvoTrees = "0.14.7, 0.15"
diff --git a/test/aqua.jl b/test/aqua.jl
new file mode 100644
index 00000000..e6226e77
--- /dev/null
+++ b/test/aqua.jl
@@ -0,0 +1,16 @@
+using MCMCDiagnosticTools
+using Aqua
+using Test
+
+@testset "Aqua" begin
+    # Test ambiguities separately without Base and Core
+    # Ref: https://github.com/JuliaTesting/Aqua.jl/issues/77
+    # Only test Project.toml formatting on Julia > 1.6 when running Github action
+    # Ref: https://github.com/JuliaTesting/Aqua.jl/issues/105
+    Aqua.test_all(
+        MCMCDiagnosticTools;
+        ambiguities=false,
+        project_toml_formatting=VERSION >= v"1.7" || !haskey(ENV, "GITHUB_ACTIONS"),
+    )
+    Aqua.test_ambiguities([MCMCDiagnosticTools])
+end
diff --git a/test/rstar.jl b/test/rstar.jl
index 848fb221..1550c38b 100644
--- a/test/rstar.jl
+++ b/test/rstar.jl
@@ -188,4 +188,14 @@ end
         )
         @test_throws ArgumentError MCMCDiagnosticTools._rstar(1.0, rand(2), rand(2))
     end
+
+    @testset "single chain: method ambiguity issue" begin
+        samples = rand(1:5, N)
+        rng = MersenneTwister(42)
+        dist = rstar(rng, DecisionTreeClassifier(), samples)
+        @test mean(dist) ≈ 1 atol = 0.15
+        Random.seed!(rng, 42)
+        dist2 = rstar(rng, DecisionTreeClassifier(), samples, ones(Int, N))
+        @test dist2 == dist
+    end
 end
diff --git a/test/runtests.jl b/test/runtests.jl
index b756fbe2..07f52402 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -10,6 +10,10 @@ Random.seed!(1)
 @testset "MCMCDiagnosticTools.jl" begin
     include("helpers.jl")
 
+    @testset "Aqua" begin
+        include("aqua.jl")
+    end
+
     @testset "utils" begin
         include("utils.jl")
     end