diff --git a/.github/workflows/prototyping.yml b/.github/workflows/prototyping.yml
index 62881fcd..53ca3c54 100644
--- a/.github/workflows/prototyping.yml
+++ b/.github/workflows/prototyping.yml
@@ -11,10 +11,7 @@ jobs:
     strategy:
       matrix:
         agda: [2.6.2.1]
-        bytestring: [0.11.1.0]
-        scientific: [0.3.7.0]
-        vector: [0.12.3.1]
-        aeson: [2.0.3.0]
+        hackage: [2022-01-31T23:42:28Z]
     name: prototyping
     runs-on: ubuntu-latest
     steps:
@@ -22,7 +19,7 @@ jobs:
     - uses: actions/cache@v2
       with:
         path: ~/.cabal/store
-        key: prototyping-${{ runner.os }}-${{ matrix.agda }}
+        key: prototyping-${{ runner.os }}-${{ matrix.agda }}-${{ matrix.hackage }}
     - uses: actions/cache@v2
       id: luau-ast-cache
       with:
@@ -32,12 +29,12 @@ jobs:
       run: sudo apt-get install -y cabal-install
     - name: cabal update
       working-directory: prototyping
-      run: cabal update
+      run: cabal v2-update hackage.haskell.org,${{ matrix.hackage }}
     - name: cabal install
       working-directory: prototyping
       run: |
         cabal install Agda-${{ matrix.agda }}
-        cabal install --lib bytestring-${{ matrix.bytestring }} scientific-${{ matrix.scientific }} vector-${{ matrix.vector }} aeson-${{ matrix.aeson }} --package-env .
+        cabal install --lib scientific vector aeson --package-env .
     - name: check targets
       working-directory: prototyping
       run: |