diff --git a/src/CMBLensing.jl b/src/CMBLensing.jl
index f1cbdd38..d5db4bb0 100644
--- a/src/CMBLensing.jl
+++ b/src/CMBLensing.jl
@@ -51,7 +51,7 @@ using Serialization
 using Setfield
 using SparseArrays
 using StaticArrays: @SMatrix, @SVector, SMatrix, StaticArray, StaticArrayStyle,
-    StaticMatrix, StaticVector, SVector, SArray, SizedArray
+    StaticMatrix, StaticVector, SVector, SArray, SizedArray, SizedMatrix
 using Statistics
 using StatsBase
 using TimerOutputs: @timeit, get_defaulttimer, reset_timer!
diff --git a/src/field_vectors.jl b/src/field_vectors.jl
index f8a5d1ef..dbae81a7 100644
--- a/src/field_vectors.jl
+++ b/src/field_vectors.jl
@@ -65,4 +65,3 @@ function pinv!(dst::FieldOrOpMatrix{<:Diagonal}, src::FieldOrOpMatrix{<:Diagonal
 end
 
 promote_rule(::Type{F}, ::Type{<:Scalar}) where {F<:Field} = F
-arithmetic_closure(::F) where {F<:Field} = F
diff --git a/src/generic.jl b/src/generic.jl
index 891e99b9..010bea01 100644
--- a/src/generic.jl
+++ b/src/generic.jl
@@ -322,6 +322,7 @@ precompute!!(L::Adjoint, f) = precompute!!(parent(L),f)'
 # splatted into a giant matrix when doing [f f; f f] (which they would othewise
 # be since they're Arrays)
 hvcat(rows::Tuple{Vararg{Int}}, values::Field...) = hvcat(rows, ([x] for x in values)...)
+hvcat(rows::Tuple{Vararg{Int}}, values::DiagOp...) = hvcat(rows, ([x] for x in values)...)
 hcat(values::Field...) = hcat(([x] for x in values)...)
 
 ### printing
diff --git a/src/proj_lambert.jl b/src/proj_lambert.jl
index f49be830..84f92624 100644
--- a/src/proj_lambert.jl
+++ b/src/proj_lambert.jl
@@ -366,7 +366,7 @@ function Cℓ_to_Cov(::Val{:P}, proj::ProjLambert, CℓEE::Cℓs, CℓBB::Cℓs;
 end
 function Cℓ_to_Cov(::Val{:IP}, proj::ProjLambert, CℓTT, CℓEE, CℓBB, CℓTE; kwargs...)
     ΣTT, ΣEE, ΣBB, ΣTE = [Cℓ_to_Cov(:I,proj,Cℓ; kwargs...) for Cℓ in (CℓTT,CℓEE,CℓBB,CℓTE)]
-    BlockDiagIEB(@SMatrix([ΣTT ΣTE; ΣTE ΣEE]), ΣBB)
+    BlockDiagIEB([ΣTT ΣTE; ΣTE ΣEE], ΣBB)
 end
 
 ## ParamDependentOp covariances scaled by amplitudes in different ℓ-bins
diff --git a/src/specialops.jl b/src/specialops.jl
index 86647321..74c0efc3 100644
--- a/src/specialops.jl
+++ b/src/specialops.jl
@@ -57,9 +57,10 @@ end
 # call sqrt/inv on it, and the ΣBB block separately as ΣB. This type
 # is generic with regards to the field type, F.
 struct BlockDiagIEB{T,F} <: ImplicitOp{T}
-    ΣTE :: SMatrix{2,2,Diagonal{T,F},4}
+    ΣTE :: SizedMatrix{2,2,Diagonal{T,F},2,Matrix{Diagonal{T,F}}}
     ΣB :: Diagonal{T,F}
 end
+BlockDiagIEB(ΣTE::AbstractMatrix{Diagonal{T,F}}, ΣB::Diagonal{T,F}) where {T,F} = BlockDiagIEB{T,F}(ΣTE, ΣB)
 # applying
 *(L::BlockDiagIEB, f::BaseS02) =       L * IEBFourier(f)
 \(L::BlockDiagIEB, f::BaseS02) = pinv(L) * IEBFourier(f)
@@ -77,13 +78,13 @@ similar(L::BlockDiagIEB) = BlockDiagIEB(similar.(L.ΣTE), similar(L.ΣB))
 get_storage(L::BlockDiagIEB) = get_storage(L.ΣB)
 adapt_structure(storage, L::BlockDiagIEB) = BlockDiagIEB(adapt.(Ref(storage), L.ΣTE), adapt(storage, L.ΣB))
 simulate(rng::AbstractRNG, L::BlockDiagIEB; Nbatch=()) = sqrt(L) * randn!(rng, similar(diag(L), Nbatch...))
-logdet(L::BlockDiagIEB) = logdet(L.ΣTE[1,1]*L.ΣTE[2,2]-L.ΣTE[1,2]*L.ΣTE[2,1]) + logdet(L.ΣB)
+logdet(L::BlockDiagIEB) = logdet(det(L.ΣTE)) + logdet(L.ΣB)
 # arithmetic
-*(L::BlockDiagIEB, D::DiagOp{<:BaseIEBFourier}) = BlockDiagIEB(SMatrix{2,2}(L.ΣTE * [[D[:I]] [0]; [0] [D[:E]]]), L.ΣB * D[:B])
-+(L::BlockDiagIEB, D::DiagOp{<:BaseIEBFourier}) = BlockDiagIEB(@SMatrix[L.ΣTE[1,1]+D[:I] L.ΣTE[1,2]; L.ΣTE[2,1] L.ΣTE[2,2]+D[:E]], L.ΣB + D[:B])
+*(L::BlockDiagIEB, D::DiagOp{<:BaseIEBFourier}) = BlockDiagIEB(L.ΣTE * [[D[:I]] [0]; [0] [D[:E]]], L.ΣB * D[:B])
++(L::BlockDiagIEB, D::DiagOp{<:BaseIEBFourier}) = BlockDiagIEB([L.ΣTE[1,1]+D[:I] L.ΣTE[1,2]; L.ΣTE[2,1] L.ΣTE[2,2]+D[:E]], L.ΣB + D[:B])
 *(La::F, Lb::F) where {F<:BlockDiagIEB} = F(La.ΣTE * Lb.ΣTE, La.ΣB * Lb.ΣB)
 +(La::F, Lb::F) where {F<:BlockDiagIEB} = F(La.ΣTE + Lb.ΣTE, La.ΣB + Lb.ΣB)
-+(L::BlockDiagIEB, U::UniformScaling{<:Scalar}) = BlockDiagIEB(@SMatrix[(L.ΣTE[1,1]+U) L.ΣTE[1,2]; L.ΣTE[2,1] (L.ΣTE[2,2]+U)], L.ΣB+U)
++(L::BlockDiagIEB, U::UniformScaling{<:Scalar}) = BlockDiagIEB([(L.ΣTE[1,1]+U) L.ΣTE[1,2]; L.ΣTE[2,1] (L.ΣTE[2,2]+U)], L.ΣB+U)
 *(L::BlockDiagIEB, λ::Scalar) = BlockDiagIEB(L.ΣTE * λ, L.ΣB * λ)
 *(D::DiagOp{<:BaseIEBFourier}, L::BlockDiagIEB) = L * D
 +(U::UniformScaling{<:Scalar}, L::BlockDiagIEB) = L + U
diff --git a/src/util.jl b/src/util.jl
index 66322e43..9c765f6a 100644
--- a/src/util.jl
+++ b/src/util.jl
@@ -100,20 +100,25 @@ end
 # these allow pinv and sqrt of SMatrices of Diagonals to work correctly, which
 # we use for the T-E block of the covariance. hopefully some of this can be cut
 # down on in the futue with some PRs into StaticArrays.
-permutedims(A::SMatrix{2,2}) = @SMatrix[A[1] A[3]; A[2] A[4]]
-@auto_adjoint function sqrt(A::SMatrix{2,2,<:Diagonal})
+# permutedims(A::SMatrix{2,2}) = @SMatrix[A[1] A[3]; A[2] A[4]]
+@auto_adjoint function sqrt(A::SizedMatrix{2,2,<:Diagonal})
     # A = [a b; c d]
     a,c,b,d = A 
     s = sqrt(a*d-b*c)
     t = pinv(sqrt(a+(d+2s)))
     @SMatrix[t*(a+s) t*b; t*c t*(d+s)]
 end
-@auto_adjoint function pinv(A::SMatrix{2,2,<:Diagonal})
+@auto_adjoint function pinv(A::SizedMatrix{2,2,<:Diagonal})
     # A = [a b; c d]
     a,c,b,d = A 
     idet = pinv(a*d-b*c)
     @SMatrix[d*idet -(b*idet); -(c*idet) a*idet]
 end
+@auto_adjoint function det(A::SizedMatrix{2,2,<:Diagonal})
+    # A = [a b; c d]
+    a,c,b,d = A 
+    a*d-b*c
+end
 
 
 # some usefule tuple manipulation functions: