diff --git a/.github/workflows/main_test_itensors_base_macos_windows.yml b/.github/workflows/main_test_itensors_base_macos_windows.yml
index a92e581dd6..f9f39d16fd 100644
--- a/.github/workflows/main_test_itensors_base_macos_windows.yml
+++ b/.github/workflows/main_test_itensors_base_macos_windows.yml
@@ -14,7 +14,7 @@ jobs:
     strategy:
       matrix:
         version:
-          - '1.6'
+          - 'lts'
           - '1'
         os:
           # - windows-latest # windows tests are failing for an unknow reason, disable for now
diff --git a/.github/workflows/test_itensormps_ubuntu.yml b/.github/workflows/test_itensormps_ubuntu.yml
index fb81c37280..cf80a2a8b3 100644
--- a/.github/workflows/test_itensormps_ubuntu.yml
+++ b/.github/workflows/test_itensormps_ubuntu.yml
@@ -16,7 +16,7 @@ jobs:
     strategy:
       matrix:
         version:
-          - '1.6'
+          - 'lts'
           - '1'
         os:
           - ubuntu-latest
diff --git a/.github/workflows/test_itensors_base_ubuntu.yml b/.github/workflows/test_itensors_base_ubuntu.yml
index d185c5de56..7004dae0f7 100644
--- a/.github/workflows/test_itensors_base_ubuntu.yml
+++ b/.github/workflows/test_itensors_base_ubuntu.yml
@@ -16,7 +16,7 @@ jobs:
     strategy:
       matrix:
         version:
-          - '1.6'
+          - 'lts'
           - '1'
         os:
           - ubuntu-latest
diff --git a/.github/workflows/test_ndtensors.yml b/.github/workflows/test_ndtensors.yml
index 67a46f39b0..1f3f4c8be1 100644
--- a/.github/workflows/test_ndtensors.yml
+++ b/.github/workflows/test_ndtensors.yml
@@ -16,7 +16,7 @@ jobs:
     strategy:
       matrix:
         version:
-          - '1.6'
+          - 'lts'
           - '1'
         os:
           - ubuntu-latest
diff --git a/NDTensors/Project.toml b/NDTensors/Project.toml
index 65771b0c5a..cdfd6102bb 100644
--- a/NDTensors/Project.toml
+++ b/NDTensors/Project.toml
@@ -1,7 +1,7 @@
 name = "NDTensors"
 uuid = "23ae76d9-e61a-49c4-8f12-3f1a16adf9cf"
 authors = ["Matthew Fishman <mfishman@flatironinstitute.org>"]
-version = "0.3.43"
+version = "0.3.46"
 
 [deps]
 Accessors = "7d9f7c33-5ae7-4f3b-8dc6-eff91059b697"
@@ -68,7 +68,7 @@ EllipsisNotation = "1.8"
 FillArrays = "1"
 Folds = "0.2.8"
 Functors = "0.2, 0.3, 0.4"
-GPUArraysCore = "0.1"
+GPUArraysCore = "0.1, 0.2"
 HDF5 = "0.14, 0.15, 0.16, 0.17"
 HalfIntegers = "1"
 InlineStrings = "1"
@@ -91,7 +91,7 @@ TimerOutputs = "0.5.5"
 TupleTools = "1.2.0"
 VectorInterface = "0.4.2"
 cuTENSOR = "2"
-julia = "1.6"
+julia = "1.10"
 
 [extras]
 AMDGPU = "21141c5a-9bdb-4563-92ae-f87d6854732e"
diff --git a/NDTensors/src/empty/EmptyTensor.jl b/NDTensors/src/empty/EmptyTensor.jl
index 3fcbf4ed63..f5e04e0652 100644
--- a/NDTensors/src/empty/EmptyTensor.jl
+++ b/NDTensors/src/empty/EmptyTensor.jl
@@ -152,8 +152,6 @@ end
 
 setindex!!(T::EmptyTensor, x, I...) = setindex(T, x, I...)
 
-promote_rule(::Type{EmptyNumber}, ::Type{T}) where {T<:Number} = T
-
 function promote_rule(
   ::Type{T1}, ::Type{T2}
 ) where {T1<:EmptyStorage{EmptyNumber},T2<:TensorStorage}
diff --git a/NDTensors/src/emptynumber.jl b/NDTensors/src/emptynumber.jl
index d84abb52ca..1d9799b740 100644
--- a/NDTensors/src/emptynumber.jl
+++ b/NDTensors/src/emptynumber.jl
@@ -18,6 +18,14 @@ convert(::Type{T}, x::EmptyNumber) where {T<:Number} = T(zero(T))
 # This helps with defining `norm` of `EmptyStorage{EmptyNumber}`.
 AbstractFloat(::EmptyNumber) = zero(AbstractFloat)
 
+# Extra definitions fix ambiguity errors.
+Base.promote_rule(::Type{EmptyNumber}, T::Type{<:Number}) = T
+Base.promote_rule(T::Type{<:Number}, ::Type{EmptyNumber}) = T
+Base.promote_rule(::Type{EmptyNumber}, ::Type{Bool}) = Bool
+Base.promote_rule(::Type{Bool}, ::Type{EmptyNumber}) = Bool
+Base.promote_rule(::Type{EmptyNumber}, T::Type{Complex{R}}) where {R<:Real} = T
+Base.promote_rule(T::Type{Complex{R}}, ::Type{EmptyNumber}) where {R<:Real} = T
+
 # Basic arithmetic
 (::EmptyNumber + ::EmptyNumber) = EmptyNumber()
 (::EmptyNumber - ::EmptyNumber) = EmptyNumber()
diff --git a/NDTensors/src/lib/BlockSparseArrays/test/test_basics.jl b/NDTensors/src/lib/BlockSparseArrays/test/test_basics.jl
index 10f8d6e35d..a7797766d4 100644
--- a/NDTensors/src/lib/BlockSparseArrays/test/test_basics.jl
+++ b/NDTensors/src/lib/BlockSparseArrays/test/test_basics.jl
@@ -597,21 +597,31 @@ include("TestBlockSparseArraysUtils.jl")
     c = @view b[4:8, 4:8]
     @test c isa SubArray{<:Any,<:Any,<:BlockSparseArray}
     @test size(c) == (5, 5)
-    @test block_nstored(c) == 2
+    # TODO: Fix in Julia 1.11 (https://github.com/ITensor/ITensors.jl/pull/1539).
+    @test block_nstored(c) == 2 broken = VERSION > v"1.11-"
     @test blocksize(c) == (2, 2)
     @test blocklengths.(axes(c)) == ([2, 3], [2, 3])
-    @test size(c[Block(1, 1)]) == (2, 2)
-    @test c[Block(1, 1)] == a[Block(2, 2)[2:3, 2:3]]
-    @test size(c[Block(2, 2)]) == (3, 3)
-    @test c[Block(2, 2)] == a[Block(1, 1)[1:3, 1:3]]
-    @test size(c[Block(2, 1)]) == (3, 2)
-    @test iszero(c[Block(2, 1)])
-    @test size(c[Block(1, 2)]) == (2, 3)
-    @test iszero(c[Block(1, 2)])
+    # TODO: Fix in Julia 1.11 (https://github.com/ITensor/ITensors.jl/pull/1539).
+    @test size(c[Block(1, 1)]) == (2, 2) broken = VERSION ≥ v"1.11-"
+    # TODO: Fix in Julia 1.11 (https://github.com/ITensor/ITensors.jl/pull/1539).
+    @test c[Block(1, 1)] == a[Block(2, 2)[2:3, 2:3]] broken = VERSION ≥ v"1.11-"
+    # TODO: Fix in Julia 1.11 (https://github.com/ITensor/ITensors.jl/pull/1539).
+    @test size(c[Block(2, 2)]) == (3, 3) broken = VERSION ≥ v"1.11-"
+    # TODO: Fix in Julia 1.11 (https://github.com/ITensor/ITensors.jl/pull/1539).
+    @test c[Block(2, 2)] == a[Block(1, 1)[1:3, 1:3]] broken = VERSION ≥ v"1.11-"
+    # TODO: Fix in Julia 1.11 (https://github.com/ITensor/ITensors.jl/pull/1539).
+    @test size(c[Block(2, 1)]) == (3, 2) broken = VERSION ≥ v"1.11-"
+    # TODO: Fix in Julia 1.11 (https://github.com/ITensor/ITensors.jl/pull/1539).
+    @test iszero(c[Block(2, 1)]) broken = VERSION ≥ v"1.11-"
+    # TODO: Fix in Julia 1.11 (https://github.com/ITensor/ITensors.jl/pull/1539).
+    @test size(c[Block(1, 2)]) == (2, 3) broken = VERSION ≥ v"1.11-"
+    # TODO: Fix in Julia 1.11 (https://github.com/ITensor/ITensors.jl/pull/1539).
+    @test iszero(c[Block(1, 2)]) broken = VERSION ≥ v"1.11-"
 
     x = randn(elt, 3, 3)
     c[Block(2, 2)] = x
-    @test c[Block(2, 2)] == x
+    # TODO: Fix in Julia 1.11 (https://github.com/ITensor/ITensors.jl/pull/1539).
+    @test c[Block(2, 2)] == x broken = VERSION ≥ v"1.11-"
     @test a[Block(1, 1)[1:3, 1:3]] == x
 
     a = BlockSparseArray{elt}([2, 3], [3, 4])
@@ -637,10 +647,13 @@ include("TestBlockSparseArraysUtils.jl")
       @test copy(b) == a
       @test blocksize(b) == (2, 2)
       @test blocklengths.(axes(b)) == ([4, 4], [4, 4])
-      @test b[Block(1, 1)] == a[Block.(1:2), Block.(1:2)]
-      @test b[Block(2, 1)] == a[Block.(3:4), Block.(1:2)]
-      @test b[Block(1, 2)] == a[Block.(1:2), Block.(3:4)]
-      @test b[Block(2, 2)] == a[Block.(3:4), Block.(3:4)]
+      # TODO: Fix in Julia 1.11 (https://github.com/ITensor/ITensors.jl/pull/1539).
+      if VERSION < v"1.11-"
+        @test b[Block(1, 1)] == a[Block.(1:2), Block.(1:2)]
+        @test b[Block(2, 1)] == a[Block.(3:4), Block.(1:2)]
+        @test b[Block(1, 2)] == a[Block.(1:2), Block.(3:4)]
+        @test b[Block(2, 2)] == a[Block.(3:4), Block.(3:4)]
+      end
       c = @view b[Block(2, 2)]
       @test blocksize(c) == (1, 1)
       @test c == a[Block.(3:4), Block.(3:4)]
@@ -669,13 +682,17 @@ include("TestBlockSparseArraysUtils.jl")
       @test copy(b) == a[J, J]
       @test blocksize(b) == (2, 2)
       @test blocklengths.(axes(b)) == ([4, 4], [4, 4])
-      @test b[Block(1, 1)] == Array(a)[[7, 8, 5, 6], [7, 8, 5, 6]]
+      # TODO: Fix in Julia 1.11 (https://github.com/ITensor/ITensors.jl/pull/1539).
+      @test b[Block(1, 1)] == Array(a)[[7, 8, 5, 6], [7, 8, 5, 6]] broken =
+        VERSION ≥ v"1.11-"
       c = @views b[Block(1, 1)][2:3, 2:3]
       @test c == Array(a)[[8, 5], [8, 5]]
-      @test copy(c) == Array(a)[[8, 5], [8, 5]]
+      # TODO: Fix in Julia 1.11 (https://github.com/ITensor/ITensors.jl/pull/1539).
+      @test copy(c) == Array(a)[[8, 5], [8, 5]] broken = VERSION ≥ v"1.11-"
       c = @view b[Block(1, 1)[2:3, 2:3]]
       @test c == Array(a)[[8, 5], [8, 5]]
-      @test copy(c) == Array(a)[[8, 5], [8, 5]]
+      # TODO: Fix in Julia 1.11 (https://github.com/ITensor/ITensors.jl/pull/1539).
+      @test copy(c) == Array(a)[[8, 5], [8, 5]] broken = VERSION ≥ v"1.11-"
     end
 
     # TODO: Add more tests of this, it may
diff --git a/NDTensors/src/lib/LabelledNumbers/src/labelledunitrange.jl b/NDTensors/src/lib/LabelledNumbers/src/labelledunitrange.jl
index 2e4379daba..a82c666987 100644
--- a/NDTensors/src/lib/LabelledNumbers/src/labelledunitrange.jl
+++ b/NDTensors/src/lib/LabelledNumbers/src/labelledunitrange.jl
@@ -37,6 +37,17 @@ end
 
 labelled_getindex(a, index) = labelled(unlabel(a)[index], label(a))
 
+# This is required in Julia 1.11 and above since
+# the generic `axes(a::AbstractRange)` definition was removed
+# and replace with a generic `axes(a)` definition that
+# is written in terms of `Base.unchecked_oneto`, i.e.:
+# ```julia
+# map(Base.unchecked_oneto, size(A))
+# ```
+# which returns a `Base.OneTo` instead of a `LabelledUnitRange`.
+Base.axes(a::LabelledUnitRange) = Base.oneto.(size(a))
+
+# TODO: Delete this definition, this should output a `Base.OneTo`.
 Base.OneTo(stop::LabelledInteger) = labelled(Base.OneTo(unlabel(stop)), label(stop))
 
 # Fix ambiguity error with `AbstractRange` definition in `Base`.
diff --git a/NDTensors/test/Project.toml b/NDTensors/test/Project.toml
index 5244d98895..15787f7fbb 100644
--- a/NDTensors/test/Project.toml
+++ b/NDTensors/test/Project.toml
@@ -18,7 +18,6 @@ Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 SafeTestsets = "1bc83da4-3b8d-516f-aca4-4fe02f6d838f"
 SparseArrays = "2f01184e-e22b-5df5-ae63-d93ebab69eaf"
 StridedViews = "4db3bf67-4bd7-4b4e-b153-31dc3fb37143"
-TBLIS = "48530278-0828-4a49-9772-0f3830dfa1e9"
 TensorOperations = "6aa20fa7-93e2-5fca-9bc0-fbd0db3c71a2"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 Zygote = "e88e6eb3-aa80-5325-afca-941959d7151f"
@@ -30,5 +29,6 @@ Metal = "1.1.0"
 [extras]
 AMDGPU = "21141c5a-9bdb-4563-92ae-f87d6854732e"
 CUDA = "052768ef-5323-5732-b1bb-66c8b64840ba"
-Metal = "dde4c033-4e86-420c-a63e-0dd931031962"
 cuTENSOR = "011b41b2-24ef-40a8-b3eb-fa098493e9e1"
+Metal = "dde4c033-4e86-420c-a63e-0dd931031962"
+TBLIS = "48530278-0828-4a49-9772-0f3830dfa1e9"
diff --git a/NDTensors/test/test_dense.jl b/NDTensors/test/test_dense.jl
index 94c52f4132..c2b327811a 100644
--- a/NDTensors/test/test_dense.jl
+++ b/NDTensors/test/test_dense.jl
@@ -83,6 +83,20 @@ NDTensors.dim(i::MyInd) = i.dim
         @test A[2, 2] == Aview[1, 1]
       end
 
+      ## Testing A .= α .* B .+ β .* A
+      C = copy(A)
+      @allowscalar fill!(B, zero(elt))
+      β = elt(2)
+      α = elt(1)
+      permutedims!!(A, B, (1, 2), (a, b) -> +(*(β, a), *(α, b)))
+      @allowscalar 2 .* C == A
+      randn!(B)
+      C = copy(A)
+      A = permutedims!!(A, B, (1, 2), (a, b) -> +(*(β, a), *(α, b)))
+      @allowscalar for i in 1:3, j in 1:4
+        @test A[i, j] == α * B[i, j] + β * C[i, j]
+      end
+
       ## add elt around 2.0 to preserve the eltype of A.
       @test data(A * elt(2.0)) == data(elt(2.0) * A)
 
diff --git a/NDTensors/test/test_emptynumber.jl b/NDTensors/test/test_emptynumber.jl
index dc8357a115..73d82117f5 100644
--- a/NDTensors/test/test_emptynumber.jl
+++ b/NDTensors/test/test_emptynumber.jl
@@ -1,14 +1,21 @@
 @eval module $(gensym())
-using NDTensors
+using LinearAlgebra: norm
+using NDTensors: EmptyNumber
 using Test: @testset, @test, @test_throws
 
-const 𝟎 = NDTensors.EmptyNumber()
+const 𝟎 = EmptyNumber()
 
 @testset "NDTensors.EmptyNumber" begin
   x = 2.3
 
   @test complex(𝟎) == 𝟎
-  @test complex(NDTensors.EmptyNumber) == Complex{NDTensors.EmptyNumber}
+  @test complex(EmptyNumber) == Complex{EmptyNumber}
+
+  # Promotion
+  for T in (Bool, Float32, Float64, Complex{Float32}, Complex{Float64})
+    @test promote_type(EmptyNumber, T) === T
+    @test promote_type(T, EmptyNumber) === T
+  end
 
   # Basic arithmetic
   @test 𝟎 + 𝟎 == 𝟎
diff --git a/Project.toml b/Project.toml
index 0e9b91a39e..f7f9e50b0a 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "ITensors"
 uuid = "9136182c-28ba-11e9-034c-db9fb085ebd5"
 authors = ["Matthew Fishman <mfishman@flatironinstitute.org>", "Miles Stoudenmire <mstoudenmire@flatironinstitute.org>"]
-version = "0.6.19"
+version = "0.6.22"
 
 [deps]
 Adapt = "79e6a3ab-5dfb-504d-930d-738a2a938a0e"
@@ -73,7 +73,7 @@ TupleTools = "1.2"
 VectorInterface = "0.4"
 Zeros = "0.3.0"
 ZygoteRules = "0.2.2"
-julia = "1.6"
+julia = "1.10"
 
 [extras]
 ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"
diff --git a/ext/ITensorsPackageCompilerExt/ITensorsPackageCompilerExt.jl b/ext/ITensorsPackageCompilerExt/ITensorsPackageCompilerExt.jl
index 78b7166e74..3bb7b57ac1 100644
--- a/ext/ITensorsPackageCompilerExt/ITensorsPackageCompilerExt.jl
+++ b/ext/ITensorsPackageCompilerExt/ITensorsPackageCompilerExt.jl
@@ -1,4 +1,3 @@
 module ITensorsPackageCompilerExt
 include("compile.jl")
-include("precompile_itensors.jl")
 end
diff --git a/jenkins/Dockerfile b/jenkins/Dockerfile
index c677086f2f..e2367a8c01 100644
--- a/jenkins/Dockerfile
+++ b/jenkins/Dockerfile
@@ -13,4 +13,4 @@ RUN apt-get update && \
 
 ARG JULIA=1.6
 RUN curl -s -L https://julialang-s3.julialang.org/bin/linux/x64/${JULIA}/julia-${JULIA}-latest-linux-x86_64.tar.gz | \
-    tar -C /usr/local -x -z --strip-components=1 -f -
+    tar -C /usr/local -x -z --strip-components=1 -f -
\ No newline at end of file
diff --git a/jenkins/Jenkinsfile b/jenkins/Jenkinsfile
index 5ac7f6a62b..4fd308d59a 100644
--- a/jenkins/Jenkinsfile
+++ b/jenkins/Jenkinsfile
@@ -7,7 +7,7 @@ pipeline {
   stages {
     stage('GPU Testing') {
       parallel {
-        stage('NDTensorsCUDAExt julia-1.10') {
+        stage('NDTensorsCUDAExt julia-lts') {
 	        options {
             timeout(time: 45, unit: 'MINUTES')
           }
@@ -31,7 +31,31 @@ pipeline {
             '''
           }
         }
-        stage('NDTensorscuTENSORExt julia-1.10') {
+        stage('NDTensorsCUDAExt julia-1') {
+	        options {
+            timeout(time: 45, unit: 'MINUTES')
+          }
+          agent {
+            dockerfile {
+              label 'gpu&&v100'
+              filename 'Dockerfile'
+              dir 'jenkins'
+              additionalBuildArgs  '--build-arg JULIA=1.11'
+              args '--gpus "device=1"'
+            }
+          }
+          environment {
+            HOME = pwd(tmp:true)
+            OMP_NUM_THREADS = 4
+            JULIA_NUM_THREADS = 4
+          }
+          steps {
+            sh '''
+              julia -e 'using Pkg; Pkg.activate(temp=true); Pkg.Registry.update(); Pkg.update(); Pkg.develop(path="./NDTensors"); Pkg.develop(path="."); Pkg.test("NDTensors"; test_args=["cuda"])'
+            '''
+          }
+        }
+        stage('NDTensorscuTENSORExt julia-lts') {
 	        options {
             timeout(time: 45, unit: 'MINUTES')
           }
@@ -55,7 +79,52 @@ pipeline {
             '''
           }
         }
-        stage('NDTensorsMetalExt Julia-1.10'){
+        stage('NDTensorscuTENSORExt julia-1') {
+	        options {
+            timeout(time: 45, unit: 'MINUTES')
+          }
+          agent {
+            dockerfile {
+              label 'gpu&&v100'
+              filename 'Dockerfile'
+              dir 'jenkins'
+              additionalBuildArgs  '--build-arg JULIA=1.11'
+              args '--gpus "device=1"'
+            }
+          }
+          environment {
+            HOME = pwd(tmp:true)
+            OMP_NUM_THREADS = 4
+            JULIA_NUM_THREADS = 4
+          }
+          steps {
+            sh '''
+              julia -e 'using Pkg; Pkg.activate(temp=true); Pkg.Registry.update(); Pkg.update(); Pkg.develop(path="./NDTensors"); Pkg.develop(path="."); Pkg.test("NDTensors"; test_args=["cutensor"])'
+            '''
+          }
+        }
+        stage('NDTensorsMetalExt Julia-lts'){
+          options {
+            timeout(time: 45, unit: 'MINUTES')
+          }
+          agent {
+            label 'm1'
+          }
+          environment{
+            PATH="${env.HOME}/.juliaup/bin:${env.PATH}"
+            PLATFORM = 'macos'
+          }
+          steps{
+            sh '''
+              juliaup add lts
+              juliaup default lts
+            '''
+            sh '''
+              julia -e 'using Pkg; Pkg.activate(temp=true); Pkg.develop(path="./NDTensors"); Pkg.develop(path="."); Pkg.test("NDTensors"; test_args=["metal"])'
+            '''
+          }
+        }
+        stage('NDTensorsMetalExt Julia-1'){
           options {
             timeout(time: 45, unit: 'MINUTES')
           }
@@ -69,6 +138,7 @@ pipeline {
           steps{
             sh '''
               juliaup update
+              juliaup default release
             '''
             sh '''
               julia -e 'using Pkg; Pkg.activate(temp=true); Pkg.develop(path="./NDTensors"); Pkg.develop(path="."); Pkg.test("NDTensors"; test_args=["metal"])'
@@ -78,4 +148,4 @@ pipeline {
       }
     }
   }
-}
+}
\ No newline at end of file
diff --git a/src/broadcast.jl b/src/broadcast.jl
index 3e91d64714..4f0848d580 100644
--- a/src/broadcast.jl
+++ b/src/broadcast.jl
@@ -395,6 +395,13 @@ end
 # C .= β .* C .+ α .* A .* B
 #
 
+struct axpby{Alpha,Beta} <: Function
+  alpha::Alpha
+  beta::Beta
+end
+
+(f::axpby)(y, x) = x * f.alpha + y * f.beta
+
 ## TODO this code doesn't actually get called
 function Base.copyto!(
   T::ITensor,
@@ -414,7 +421,9 @@ function Base.copyto!(
     A, C = C, A
   end
   if !isnothing(A) && !isnothing(C) && !isnothing(α) && !isnothing(β)
-    map!((r, t) -> β * r + α * t, T, T, A)
+    # The following fails to compile on some GPU backends.
+    # map!((r, t) -> β * r + α * t, T, T, A)
+    map!(axpby(α, β), T, T, A)
   else
     bc_bc_α = find_type(Broadcasted, bc_α.args)
     if isnothing(α)
diff --git a/src/lib/ITensorMPS/test/Project.toml b/src/lib/ITensorMPS/test/Project.toml
index 127ce9e065..7345ba4285 100644
--- a/src/lib/ITensorMPS/test/Project.toml
+++ b/src/lib/ITensorMPS/test/Project.toml
@@ -6,5 +6,6 @@ ITensors = "9136182c-28ba-11e9-034c-db9fb085ebd5"
 JLD2 = "033835bb-8acc-5ee8-8aae-3f567f8a3819"
 NDTensors = "23ae76d9-e61a-49c4-8f12-3f1a16adf9cf"
 OptimKit = "77e91f04-9b3b-57a6-a776-40b61faaebe0"
+StableRNGs = "860ef19b-820b-49d6-a774-d7a799459cd3"
 Suppressor = "fd094767-a336-5f1f-9728-57cf17d0bbfb"
 Zygote = "e88e6eb3-aa80-5325-afca-941959d7151f"
diff --git a/src/lib/ITensorMPS/test/base/Project.toml b/src/lib/ITensorMPS/test/base/Project.toml
index 895d21daab..0522110b73 100644
--- a/src/lib/ITensorMPS/test/base/Project.toml
+++ b/src/lib/ITensorMPS/test/base/Project.toml
@@ -4,4 +4,5 @@ HDF5 = "f67ccb44-e63f-5c2f-98bd-6dc0ccc4ba2f"
 ITensors = "9136182c-28ba-11e9-034c-db9fb085ebd5"
 JLD2 = "033835bb-8acc-5ee8-8aae-3f567f8a3819"
 NDTensors = "23ae76d9-e61a-49c4-8f12-3f1a16adf9cf"
+StableRNGs = "860ef19b-820b-49d6-a774-d7a799459cd3"
 Suppressor = "fd094767-a336-5f1f-9728-57cf17d0bbfb"
diff --git a/src/lib/ITensorMPS/test/base/test_mpo.jl b/src/lib/ITensorMPS/test/base/test_mpo.jl
index 32746a752b..929eaa2d7b 100644
--- a/src/lib/ITensorMPS/test/base/test_mpo.jl
+++ b/src/lib/ITensorMPS/test/base/test_mpo.jl
@@ -2,6 +2,7 @@
 using Combinatorics
 using ITensors
 using NDTensors: scalartype
+using StableRNGs: StableRNG
 using Test
 
 include(joinpath(@__DIR__, "utils", "util.jl"))
@@ -812,11 +813,11 @@ end
     N = 6
     sites = [Index(2, "Site,n=$n") for n in 1:N]
     seed = 623
-    mt = MersenneTwister(seed)
-    K = random_mps(mt, sites)
+    rng = StableRNG(seed)
+    K = random_mps(rng, sites)
     L = MPO(K)
-    result = sample(mt, L)
-    @test result ≈ [1, 2, 1, 1, 2, 2]
+    result = sample(rng, L)
+    @test result ≈ [1, 1, 2, 1, 1, 1]
   end
 
   @testset "MPO+MPO sum (directsum)" begin
diff --git a/src/packagecompile/compile.jl b/src/packagecompile/compile.jl
index 0034ab0971..093e73dac3 100644
--- a/src/packagecompile/compile.jl
+++ b/src/packagecompile/compile.jl
@@ -40,12 +40,6 @@ function compile(; backend=Algorithm"PackageCompiler"(), kwargs...)
   return compile(backend; kwargs...)
 end
 
-function compile(::Algorithm; kwargs...)
-  return error(
-    "As of ITensors v0.5, you must install `PackageCompiler.jl` (`using Pkg: Pkg; Pkg.add(\"PackageCompiler\")`) and execute `using PackageCompiler` to use `ITensors.compile`.",
-  )
-end
-
 @doc """
     ITensors.compile(; dir = "$(default_compile_dir())",
                        filename = "$(default_compile_filename())")
diff --git a/test/Project.toml b/test/Project.toml
index 34fe930acb..509e3a49f0 100644
--- a/test/Project.toml
+++ b/test/Project.toml
@@ -12,9 +12,11 @@ KrylovKit = "0b1a1467-8014-51b9-945f-bf0ae24f4b77"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 NDTensors = "23ae76d9-e61a-49c4-8f12-3f1a16adf9cf"
 OptimKit = "77e91f04-9b3b-57a6-a776-40b61faaebe0"
+PackageCompiler = "9b87118b-4619-50d2-8e1e-99f35a4d4d9d"
 Pkg = "44cfe95a-1eb2-52ea-b672-e2afdf69b78f"
 QuadGK = "1fd47b50-473d-5c70-9696-f719f8f3bcdc"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
+StableRNGs = "860ef19b-820b-49d6-a774-d7a799459cd3"
 Suppressor = "fd094767-a336-5f1f-9728-57cf17d0bbfb"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 VectorInterface = "409d34a3-91d5-4945-b6ec-7529ddf182d8"
diff --git a/test/ext/ITensorsPackageCompilerExt/Project.toml b/test/ext/ITensorsPackageCompilerExt/Project.toml
new file mode 100644
index 0000000000..9b60c20322
--- /dev/null
+++ b/test/ext/ITensorsPackageCompilerExt/Project.toml
@@ -0,0 +1,4 @@
+[deps]
+ITensors = "9136182c-28ba-11e9-034c-db9fb085ebd5"
+PackageCompiler = "9b87118b-4619-50d2-8e1e-99f35a4d4d9d"
+Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
diff --git a/test/ext/ITensorsPackageCompilerExt/runtests.jl b/test/ext/ITensorsPackageCompilerExt/runtests.jl
new file mode 100644
index 0000000000..08cae7400b
--- /dev/null
+++ b/test/ext/ITensorsPackageCompilerExt/runtests.jl
@@ -0,0 +1,10 @@
+@eval module $(gensym())
+using ITensors: ITensors
+using PackageCompiler: PackageCompiler
+using Test: @testset, @test
+@testset "ITensorsPackageCompilerExt" begin
+  # Testing `ITensors.compile` would take too long so we just check
+  # that `ITensorsPackageCompilerExt` overloads `ITensors.compile`.
+  @test hasmethod(ITensors.compile, Tuple{ITensors.Algorithm"PackageCompiler"})
+end
+end
diff --git a/test/runtests.jl b/test/runtests.jl
index 60782dca54..88af73a005 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -20,6 +20,7 @@ ITensors.disable_threaded_blocksparse()
       "threading",
       "lib/ContractionSequenceOptimization",
       "ext/ITensorsChainRulesCoreExt",
+      "ext/ITensorsPackageCompilerExt",
       "ext/ITensorsVectorInterfaceExt",
     ]
     @time for dir in dirs