diff --git a/Project.toml b/Project.toml
index 1b02ba2..460f026 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,13 +1,14 @@
 name = "DerivableInterfaces"
 uuid = "6c5e35bf-e59e-4898-b73c-732dcc4ba65f"
 authors = ["ITensor developers <support@itensor.org> and contributors"]
-version = "0.5.4"
+version = "0.5.5"
 
 [deps]
 Adapt = "79e6a3ab-5dfb-504d-930d-738a2a938a0e"
 ArrayLayouts = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"
 Compat = "34da2185-b29b-5c13-b0c7-acf172513d20"
 ExproniconLite = "55351af7-c7e9-48d6-89ff-24e801d99491"
+FillArrays = "1a297f60-69ca-5386-bcde-b61e274b549b"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 MLStyle = "d8e11817-5142-5d16-987a-aa16d5891078"
 MapBroadcast = "ebd9b9da-f48d-417c-9660-449667d60261"
@@ -15,11 +16,9 @@ TypeParameterAccessors = "7e5a90cf-f82e-492e-a09b-e3e26432c138"
 
 [weakdeps]
 BlockArrays = "8e7c35d0-a365-5155-bbbb-fb81a777f24e"
-FillArrays = "1a297f60-69ca-5386-bcde-b61e274b549b"
 
 [extensions]
 DerivableInterfacesBlockArraysExt = "BlockArrays"
-DerivableInterfacesFillArraysExt = "FillArrays"
 
 [compat]
 Adapt = "4.1.1"
diff --git a/src/DerivableInterfaces.jl b/src/DerivableInterfaces.jl
index c26cccb..2db6aa3 100644
--- a/src/DerivableInterfaces.jl
+++ b/src/DerivableInterfaces.jl
@@ -15,5 +15,6 @@ include("defaultarrayinterface.jl")
 include("traits.jl")
 
 include("permuteddims.jl")
+include("fillarrays.jl")
 
 end
diff --git a/ext/DerivableInterfacesFillArraysExt/DerivableInterfacesFillArraysExt.jl b/src/fillarrays.jl
similarity index 51%
rename from ext/DerivableInterfacesFillArraysExt/DerivableInterfacesFillArraysExt.jl
rename to src/fillarrays.jl
index 9658382..aef5ae1 100644
--- a/ext/DerivableInterfacesFillArraysExt/DerivableInterfacesFillArraysExt.jl
+++ b/src/fillarrays.jl
@@ -1,11 +1,9 @@
-module DerivableInterfacesFillArraysExt
-
-using DerivableInterfaces: DerivableInterfaces
+# TODO: Turn this into a package extension, for some reson there is an issue
+# with having a package extension for both FillArrays and BlockArrays
+# in Julia v1.10.
 using FillArrays: RectDiagonal
-function DerivableInterfaces.permuteddims(a::RectDiagonal, perm)
+function permuteddims(a::RectDiagonal, perm)
   (ndims(a) == length(perm) && isperm(perm)) ||
     throw(ArgumentError("no valid permutation of dimensions"))
   return RectDiagonal(parent(a), ntuple(d -> axes(a)[perm[d]], ndims(a)))
 end
-
-end