diff --git a/stdlib/LinearAlgebra/src/diagonal.jl b/stdlib/LinearAlgebra/src/diagonal.jl
index bea8183546d90..d27da450205f7 100644
--- a/stdlib/LinearAlgebra/src/diagonal.jl
+++ b/stdlib/LinearAlgebra/src/diagonal.jl
@@ -250,6 +250,21 @@ end
 (+)(Da::Diagonal, Db::Diagonal) = Diagonal(Da.diag + Db.diag)
 (-)(Da::Diagonal, Db::Diagonal) = Diagonal(Da.diag - Db.diag)
 
+for f in (:+, :-)
+    @eval function $f(D::Diagonal{<:Number}, S::Symmetric)
+        return Symmetric($f(D, S.data), sym_uplo(S.uplo))
+    end
+    @eval function $f(S::Symmetric, D::Diagonal{<:Number})
+        return Symmetric($f(S.data, D), sym_uplo(S.uplo))
+    end
+    @eval function $f(D::Diagonal{<:Real}, H::Hermitian)
+        return Hermitian($f(D, H.data), sym_uplo(H.uplo))
+    end
+    @eval function $f(H::Hermitian, D::Diagonal{<:Real})
+        return Hermitian($f(H.data, D), sym_uplo(H.uplo))
+    end
+end
+
 (*)(x::Number, D::Diagonal) = Diagonal(x * D.diag)
 (*)(D::Diagonal, x::Number) = Diagonal(D.diag * x)
 (/)(D::Diagonal, x::Number) = Diagonal(D.diag / x)
diff --git a/stdlib/LinearAlgebra/src/special.jl b/stdlib/LinearAlgebra/src/special.jl
index 2a3b6bf2a8e00..1363708fb515f 100644
--- a/stdlib/LinearAlgebra/src/special.jl
+++ b/stdlib/LinearAlgebra/src/special.jl
@@ -264,25 +264,6 @@ function (-)(A::UniformScaling, B::Diagonal)
     Diagonal(Ref(A) .- B.diag)
 end
 
-for f in (:+, :-)
-    @eval function $f(D::Diagonal{<:Number}, S::Symmetric)
-        uplo = sym_uplo(S.uplo)
-        return Symmetric(parentof_applytri($f, Symmetric(D, uplo), S), uplo)
-    end
-    @eval function $f(S::Symmetric, D::Diagonal{<:Number})
-        uplo = sym_uplo(S.uplo)
-        return Symmetric(parentof_applytri($f, S, Symmetric(D, uplo)), uplo)
-    end
-    @eval function $f(D::Diagonal{<:Real}, H::Hermitian)
-        uplo = sym_uplo(H.uplo)
-        return Hermitian(parentof_applytri($f, Hermitian(D, uplo), H), uplo)
-    end
-    @eval function $f(H::Hermitian, D::Diagonal{<:Real})
-        uplo = sym_uplo(H.uplo)
-        return Hermitian(parentof_applytri($f, H, Hermitian(D, uplo)), uplo)
-    end
-end
-
 ## Diagonal construction from UniformScaling
 Diagonal{T}(s::UniformScaling, m::Integer) where {T} = Diagonal{T}(fill(T(s.λ), m))
 Diagonal(s::UniformScaling, m::Integer) = Diagonal{eltype(s)}(s, m)
diff --git a/stdlib/LinearAlgebra/test/special.jl b/stdlib/LinearAlgebra/test/special.jl
index 148ccd85efeb1..7e96af369e310 100644
--- a/stdlib/LinearAlgebra/test/special.jl
+++ b/stdlib/LinearAlgebra/test/special.jl
@@ -536,17 +536,4 @@ end
     @test v * S isa Matrix
 end
 
-@testset "Partly filled Hermitian and Diagonal algebra" begin
-    D = Diagonal([1,2])
-    for S in (Symmetric, Hermitian), uplo in (:U, :L)
-        M = Matrix{BigInt}(undef, 2, 2)
-        M[1,1] = M[2,2] = M[1+(uplo == :L), 1 + (uplo == :U)] = 3
-        H = S(M, uplo)
-        HM = Matrix(H)
-        @test H + D == D + H == HM + D
-        @test H - D == HM - D
-        @test D - H == D - HM
-    end
-end
-
 end # module TestSpecial