diff --git a/src/interface/orthnull.jl b/src/interface/orthnull.jl
index 64acb509..9aab7a8e 100644
--- a/src/interface/orthnull.jl
+++ b/src/interface/orthnull.jl
@@ -443,7 +443,9 @@ left_orth_alg(alg::LeftOrthAlgorithm) = alg
 left_orth_alg(alg::QRAlgorithms) = LeftOrthViaQR(alg)
 left_orth_alg(alg::PolarAlgorithms) = LeftOrthViaPolar(alg)
 left_orth_alg(alg::SVDAlgorithms) = LeftOrthViaSVD(alg)
+left_orth_alg(alg::DiagonalAlgorithm) = LeftOrthViaQR(alg)
 left_orth_alg(alg::TruncatedAlgorithm{<:SVDAlgorithms}) = LeftOrthViaSVD(alg)
+left_orth_alg(alg::TruncatedAlgorithm{DiagonalAlgorithm}) = LeftOrthViaSVD(alg)
 
 """
     right_orth_alg(alg::AbstractAlgorithm) -> RightOrthAlgorithm
@@ -478,7 +480,9 @@ right_orth_alg(alg::RightOrthAlgorithm) = alg
 right_orth_alg(alg::LQAlgorithms) = RightOrthViaLQ(alg)
 right_orth_alg(alg::PolarAlgorithms) = RightOrthViaPolar(alg)
 right_orth_alg(alg::SVDAlgorithms) = RightOrthViaSVD(alg)
+right_orth_alg(alg::DiagonalAlgorithm) = RightOrthViaLQ(alg)
 right_orth_alg(alg::TruncatedAlgorithm{<:SVDAlgorithms}) = RightOrthViaSVD(alg)
+right_orth_alg(alg::TruncatedAlgorithm{DiagonalAlgorithm}) = RightOrthViaSVD(alg)
 
 """
     left_null_alg(alg::AbstractAlgorithm) -> LeftNullAlgorithm
diff --git a/test/orthnull.jl b/test/orthnull.jl
index dec12946..084c0a9b 100644
--- a/test/orthnull.jl
+++ b/test/orthnull.jl
@@ -19,16 +19,16 @@ for T in (BLASFloats..., GenericFloats...), n in (37, m, 63)
     if T ∈ BLASFloats
         if CUDA.functional()
             TestSuite.test_orthnull(CuMatrix{T}, (m, n); test_nullity = false)
-            n == m && TestSuite.test_orthnull(Diagonal{T, CuVector{T}}, m; test_orthnull = false)
+            n == m && TestSuite.test_orthnull(Diagonal{T, CuVector{T}}, m)
         end
         if AMDGPU.functional()
             TestSuite.test_orthnull(ROCMatrix{T}, (m, n); test_nullity = false)
-            n == m && TestSuite.test_orthnull(Diagonal{T, ROCVector{T}}, m; test_orthnull = false)
+            n == m && TestSuite.test_orthnull(Diagonal{T, ROCVector{T}}, m)
         end
     end
     if !is_buildkite
         TestSuite.test_orthnull(T, (m, n))
         AT = Diagonal{T, Vector{T}}
-        TestSuite.test_orthnull(AT, m; test_orthnull = false)
+        TestSuite.test_orthnull(AT, m)
     end
 end
diff --git a/test/testsuite/TestSuite.jl b/test/testsuite/TestSuite.jl
index 2f3fde50..dfc94244 100644
--- a/test/testsuite/TestSuite.jl
+++ b/test/testsuite/TestSuite.jl
@@ -72,9 +72,11 @@ is_pivoted(alg::MatrixAlgebraKit.LQViaTransposedQR) = is_pivoted(alg.qr_alg)
 isleftcomplete(V, N) = V * V' + N * N' ≈ I
 isleftcomplete(V::AnyCuMatrix, N::AnyCuMatrix) = isleftcomplete(collect(V), collect(N))
 isleftcomplete(V::AnyROCMatrix, N::AnyROCMatrix) = isleftcomplete(collect(V), collect(N))
+isleftcomplete(V::Diagonal{T, <:ROCVector{<:T}}, N::Diagonal{T, <:ROCVector{<:T}}) where {T} = isleftcomplete(collect(V), collect(N))
 isrightcomplete(Vᴴ, Nᴴ) = Vᴴ' * Vᴴ + Nᴴ' * Nᴴ ≈ I
 isrightcomplete(V::AnyCuMatrix, N::AnyCuMatrix) = isrightcomplete(collect(V), collect(N))
 isrightcomplete(V::AnyROCMatrix, N::AnyROCMatrix) = isrightcomplete(collect(V), collect(N))
+isrightcomplete(V::Diagonal{T, <:ROCVector{<:T}}, N::Diagonal{T, <:ROCVector{<:T}}) where {T} = isrightcomplete(collect(V), collect(N))
 
 instantiate_unitary(T, A, sz) = qr_compact(randn!(similar(A, eltype(T), sz, sz)))[1]
 # AMDGPU can't generate ComplexF32 random numbers
diff --git a/test/testsuite/orthnull.jl b/test/testsuite/orthnull.jl
index 79349d2a..16b86c82 100644
--- a/test/testsuite/orthnull.jl
+++ b/test/testsuite/orthnull.jl
@@ -17,12 +17,12 @@ _right_orth_lq!(x, CVᴴ; kwargs...) = right_orth!(x, CVᴴ; alg = :lq, kwargs..
 _right_orth_polar(x; kwargs...) = right_orth(x; alg = :polar, kwargs...)
 _right_orth_polar!(x, CVᴴ; kwargs...) = right_orth!(x, CVᴴ; alg = :polar, kwargs...)
 
-function test_orthnull(T::Type, sz; test_nullity = true, test_orthnull = true, kwargs...)
+function test_orthnull(T::Type, sz; test_nullity = true, kwargs...)
     summary_str = testargs_summary(T, sz)
     return @testset "orthnull $summary_str" begin
-        test_orthnull && test_left_orthnull(T, sz; kwargs...)
+        test_left_orthnull(T, sz; kwargs...)
         test_nullity  && test_left_nullity(T, sz; kwargs...)
-        test_orthnull && test_right_orthnull(T, sz; kwargs...)
+        test_right_orthnull(T, sz; kwargs...)
         test_nullity  && test_right_nullity(T, sz; kwargs...)
     end
 end
@@ -276,9 +276,9 @@ function test_right_orthnull(
 
         # passing an algorithm
         C, Vᴴ = @testinferred right_orth(A; alg = MatrixAlgebraKit.default_lq_algorithm(A))
-        Nᴴ = @testinferred right_null(A; alg = :lq, positive = true)
         @test C isa typeof(A) && size(C) == (m, minmn)
         @test Vᴴ isa typeof(A) && size(Vᴴ) == (minmn, n)
+        Nᴴ = @testinferred right_null(A; alg = :lq, positive = true)
         @test eltype(Nᴴ) == eltype(A) && size(Nᴴ) == (n - minmn, n)
         @test C * Vᴴ ≈ A
         @test isisometric(Vᴴ; side = :right)