diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index 289c23b..552a10c 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -19,8 +19,8 @@ jobs:
   build:
     strategy:
       matrix:
-        # Test with Julia 1.6 (lowest compat version) and latest Julia 1.8
-        julia-version: ["1.6", "1.8"]
+        # Test with Julia 1.6 (lowest compat version) and latest Julia 1
+        julia-version: ["1.6", "1"]
 
     # The type of runner that the job will run on
     runs-on: ubuntu-latest
@@ -34,6 +34,12 @@ jobs:
         with:
           version: ${{ matrix.julia-version }}
 
+      - name: Cache artifacts and packages
+        uses: julia-actions/cache@v1
+        
+      # Upgrade packages (workaround for commited Manifest.toml)
+      - run: julia --project -e 'using Pkg; Pkg.instantiate(); Pkg.update()'
+
       - name: Run Pkg.build
         uses: julia-actions/julia-buildpkg@v1
 
diff --git a/Project.toml b/Project.toml
index 6f2a562..81cf742 100644
--- a/Project.toml
+++ b/Project.toml
@@ -23,4 +23,4 @@ DocOpt = "0.4 - 0.5"
 Dumper = "0.2.1"
 HDF5 = "0.15 - 0.16"
 ProgressMeter = "1"
-julia = "1.6.2 - 1.8"
+julia = "1.6.7"