diff --git a/.github/workflows/Downgrade.yml b/.github/workflows/Downgrade.yml
new file mode 100644
index 000000000..3d93f861d
--- /dev/null
+++ b/.github/workflows/Downgrade.yml
@@ -0,0 +1,31 @@
+name: Downgrade
+on:
+  pull_request:
+    branches:
+      - master
+    paths-ignore:
+      - 'docs/**'
+  push:
+    branches:
+      - master
+    paths-ignore:
+      - 'docs/**'
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        version: ['1']
+    steps:
+      - uses: actions/checkout@v3
+      - uses: julia-actions/setup-julia@v1
+        with:
+          version: ${{ matrix.version }}
+      - uses: cjdoris/julia-downgrade-compat-action@v1
+#        if: ${{ matrix.version == '1.6' }}
+        with:
+        # skip standard libraries..
+          skip: Pkg,TOML,Logging,Random,Dates,LinearAlgebra
+          strict: 'false'
+      - uses: julia-actions/julia-buildpkg@v1
+      - uses: julia-actions/julia-runtest@v1
diff --git a/Project.toml b/Project.toml
index 6d621b93d..32bc21b06 100644
--- a/Project.toml
+++ b/Project.toml
@@ -26,7 +26,7 @@ Symbolics = "0c5d862f-8b57-4792-8d23-62f2024744c7"
 TimerOutputs = "a759f4b9-e2f1-59dc-863e-4aeb61b1ea8f"
 
 [compat]
-AbstractAlgebra = "0.13, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35"
+AbstractAlgebra = "0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35"
 BenchmarkTools = "1"
 Combinatorics = "1"
 DataStructures = "0.18"
@@ -36,15 +36,15 @@ IterTools = "1"
 LinearAlgebra = "1.6, 1.7"
 Logging = "1.6, 1.7"
 MacroTools = "0.5"
-ModelingToolkit = "7, 8"
-Nemo = "0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39"
+ModelingToolkit = "8.51"
+Nemo = "0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39"
 ParamPunPam = "0.2"
-PrecompileTools = "1"
+PrecompileTools = "1.1, 1.2"
 Primes = "0.5"
 Random = "1.6, 1.7"
 SpecialFunctions = "1, 2"
 SymbolicUtils = "1"
-Symbolics = "5"
+Symbolics = "5.5"
 TestSetExtensions = "2"
 TimerOutputs = "0.5"
 julia = "1.6, 1.7"