diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 22f0fa5..d3a2a11 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -29,6 +29,7 @@ jobs:
           - 'min'
           - 'lts'
           - '1'
+          - 'nightly'
         os:
           - ubuntu-latest
           - macOS-latest
diff --git a/.github/workflows/downstream.yml b/.github/workflows/downstream.yml
index f590f8b..faa2749 100644
--- a/.github/workflows/downstream.yml
+++ b/.github/workflows/downstream.yml
@@ -36,7 +36,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        julia-version: ['1']
+        julia-version: ['1', 'nightly']
         os: [ubuntu-latest]
         package:
           - {repo: ApproxFunBase.jl, group: JuliaApproximation}
diff --git a/src/BlockSkylineMatrix.jl b/src/BlockSkylineMatrix.jl
index 633ffa6..e46fbb6 100644
--- a/src/BlockSkylineMatrix.jl
+++ b/src/BlockSkylineMatrix.jl
@@ -456,6 +456,9 @@ _parent_blocks(V::BlockBandedBlock)::Tuple{Int,Int} =
 MemoryLayout(::Type{<:BlockBandedBlock}) = ColumnMajor()
 Base.elsize(::Type{<:BlockSkylineMatrix{T,R}}) where {T,R} = Base.elsize(R)
 
+function Base.cconvert(::Type{Ptr{T}}, V::BlockBandedBlock{T}) where T
+    V
+end
 function Base.unsafe_convert(::Type{Ptr{T}}, V::BlockBandedBlock{T}) where T
     A = parent(V)
     K,J = _parent_blocks(V)
diff --git a/src/linalg.jl b/src/linalg.jl
index b018ae2..de246fc 100644
--- a/src/linalg.jl
+++ b/src/linalg.jl
@@ -106,6 +106,9 @@ strides(V::SubBlockSkylineMatrix{<:Any,LL,UU,<:Union{BlockRange1,Block1},Block1}
     (1,parent(V).block_sizes.block_strides[Int(parentindices(V)[2].block)])
 
 
+function Base.cconvert(::Type{Ptr{T}}, V::SubBlockSkylineMatrix{T,LL,UU,<:Union{BlockRange1,Block1},Block1}) where {T,LL,UU}
+    V
+end
 function unsafe_convert(::Type{Ptr{T}}, V::SubBlockSkylineMatrix{T,LL,UU,<:Union{BlockRange1,Block1},Block1}) where {T,LL,UU}
     A = parent(V)
     JR = parentindices(V)[2]
@@ -117,6 +120,9 @@ end
 strides(V::SubBlockSkylineMatrix{<:Any,LL,UU,<:BlockRange1,<:BlockIndexRange1}) where {LL,UU} =
     (1,parent(V).block_sizes.block_strides[Int(Block(parentindices(V)[2]))])
 
+function Base.cconvert(::Type{Ptr{T}}, V::SubBlockSkylineMatrix{T,LL,UU,<:BlockRange1,<:BlockIndexRange1}) where {T,LL,UU}
+    V
+end
 function unsafe_convert(::Type{Ptr{T}}, V::SubBlockSkylineMatrix{T,LL,UU,<:BlockRange1,<:BlockIndexRange1}) where {T,LL,UU}
     A = parent(V)
     JR = parentindices(V)[2]
@@ -127,6 +133,9 @@ function unsafe_convert(::Type{Ptr{T}}, V::SubBlockSkylineMatrix{T,LL,UU,<:Block
     p + sizeof(T)*(JR.block.indices[1][1]-1)*stride(V,2)
 end
 
+function Base.cconvert(::Type{Ptr{T}}, V::SubBlockSkylineMatrix{T,LL,UU,BlockIndexRange1,BlockIndexRange1}) where {T,LL,UU}
+    V
+end
 function unsafe_convert(::Type{Ptr{T}}, V::SubBlockSkylineMatrix{T,LL,UU,BlockIndexRange1,BlockIndexRange1}) where {T,LL,UU}
     A = parent(V)
     JR = parentindices(V)[2]