diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 9515ed952..7751d65ac 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -5,8 +5,12 @@ name: CI
 on: [push, pull_request]
 
 jobs:
-  main:
-    name: Run
+  setup-ebtree:
+    uses: ./.github/workflows/ebtree.yml
+    with:
+      os: ubuntu-20.04
+
+  test:
     strategy:
       # Disable `fail-fast` because even if things fail for one compiler release
       # or build flavour we still want to see how things perform with the others
@@ -15,83 +19,50 @@ jobs:
         os: [ ubuntu-20.04 ]
         dc: [ dmd-2.092.1, dmd-2.093.1 ]
         flavor: [ prod, devel ]
-        # Not a matrix row, but referenced as a constant in this file
-        ebtree_version: [ v6.0.socio10 ]
         include:
           - { dc: dmd-2.093.1, coverage: 1, closure_check: 1 }
 
     runs-on: ${{ matrix.os }}
     timeout-minutes: 30
+    needs: setup-ebtree
     steps:
-    - name: "Ensure tools/ exists"
-      run: mkdir -p ${{ github.workspace }}/tools/
-
-    - name: 'Restore ebtree ${{ matrix.ebtree_version }} from cache'
-      id: cache-ebtree
-      uses: actions/cache@v3
-      with:
-        path: ${{ github.workspace }}/tools/
-        key:  ebtree-${{ matrix.ebtree_version }}
-
-    - name: 'Checkout ebtree ${{ matrix.ebtree_version }}'
-      uses: actions/checkout@v4
-      if: steps.cache-ebtree.outputs.cache-hit != 'true'
-      with:
-        repository: sociomantic-tsunami/ebtree
-        ref: ${{ matrix.ebtree_version }}
-        # Relative to Github workspace
-        path: tools/ebtree
-
-    - name: 'Build ebtree ${{ matrix.ebtree_version }}'
-      if: steps.cache-ebtree.outputs.cache-hit != 'true'
-      run: |
-        # fpm is used to build the `.deb` and depends on ruby
-        sudo apt-get update
-        sudo apt-get install -y build-essential ruby ruby-dev
-        sudo gem install --no-document fpm
-        # Build the debian package
-        # Package lives in tools/ebtree/deb/libebtree6[-{dbg,dev}]_$VERSION-distro_arch.deb
-        # $VERSION is ${{ matrix.ebtree_version }} without the leading 'v'
-        # E.g. libebtree6[-{dbg,dev}]_6.0.socio10-bionic_amd64.deb
-        make -C '${{ github.workspace }}/tools/ebtree' deb
-
-    - name: Install dependencies
-      run: |
-        sudo apt-get update
-        sudo apt-get install -y libxslt-dev liblzo2-dev libgcrypt-dev libgpg-error-dev
-        sudo dpkg -i ${{ github.workspace }}/tools/ebtree/deb/libebtree6*.deb
+      # Checkout this repository and its submodules
+      - uses: actions/checkout@v4
+        with:
+          submodules: true
+          # Required for codecov (codecov/codecov-action#190)
+          fetch-depth: 2
 
-    - name: Install compiler
-      uses: dlang-community/setup-dlang@v1
-      with:
-        compiler: ${{ matrix.dc }}
+      - name: Install dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y libxslt-dev liblzo2-dev libgcrypt-dev libgpg-error-dev
+          sudo dpkg -i ${{ github.workspace }}/tools/ebtree/deb/libebtree6*.deb
 
-    # Checkout this repository and its submodules
-    - uses: actions/checkout@v4
-      with:
-        submodules: true
-        # Required for codecov (codecov/codecov-action#190)
-        fetch-depth: 2
+      - name: Install compiler
+        uses: dlang-community/setup-dlang@v1
+        with:
+          compiler: ${{ matrix.dc }}
 
-    - name: Test
-      run: |
-        make all test V=1 F=${{ matrix.flavor }} COV=${{ matrix.coverage }}
+      - name: Test
+        run: |
+          make all test V=1 F=${{ matrix.flavor }} COV=${{ matrix.coverage }}
 
-    - name: Test closures
-      if: ${{ matrix.closure_check == 1 }}
-      env:
-        F: ${{ matrix.flavor }}
-        DFLAGS: -vgc
-      run: |
-        # Run tests and write compiler output to temporary file
-        compiler_output=`mktemp`
-        make fasttest 2>&1 > $compiler_output
-        # Ensure there are no lines about closure allocations in the output.
-        # Note explicit check for `grep` exit status 1, i.e. no lines found.
-        ! grep -e "closure" $compiler_output
+      - name: Test closures
+        if: ${{ matrix.closure_check == 1 }}
+        env:
+          F: ${{ matrix.flavor }}
+          DFLAGS: -vgc
+        run: |
+          # Run tests and write compiler output to temporary file
+          compiler_output=`mktemp`
+          make fasttest 2>&1 > $compiler_output
+          # Ensure there are no lines about closure allocations in the output.
+          # Note explicit check for `grep` exit status 1, i.e. no lines found.
+          ! grep -e "closure" $compiler_output
 
-    - name: 'Upload coverage'
-      if: ${{ matrix.coverage == 1 }}
-      uses: codecov/codecov-action@v3
-      with:
-        flags: ${{ matrix.dc }}-${{ matrix.flavor }}
+      - name: 'Upload coverage'
+        if: ${{ matrix.coverage == 1 }}
+        uses: codecov/codecov-action@v3
+        with:
+          flags: ${{ matrix.dc }}-${{ matrix.flavor }}
diff --git a/.github/workflows/ebtree.yml b/.github/workflows/ebtree.yml
new file mode 100644
index 000000000..ad71bce43
--- /dev/null
+++ b/.github/workflows/ebtree.yml
@@ -0,0 +1,51 @@
+# Build and store ebtree in cache
+
+name: EBTree
+on:
+  workflow_call:
+    inputs:
+      os:
+        type: string
+        required: true
+      # More a constant than a real input
+      ebtree_version:
+        type: string
+        default: 'v6.0.socio10'
+
+jobs:
+  ebtree:
+    name: Build EBTree
+    runs-on: ${{ inputs.os }}
+
+    steps:
+    - name: "Ensure tools/ exists"
+      run: mkdir -p ${{ github.workspace }}/tools/
+
+    - name: 'Restore ebtree ${{ inputs.ebtree_version }} from cache'
+      id: cache-ebtree
+      uses: actions/cache@v3
+      with:
+        path: ${{ github.workspace }}/tools/
+        key:  ebtree-${{ inputs.ebtree_version }}
+
+    - name: 'Checkout ebtree ${{ inputs.ebtree_version }}'
+      uses: actions/checkout@v4
+      if: steps.cache-ebtree.outputs.cache-hit != 'true'
+      with:
+        repository: sociomantic-tsunami/ebtree
+        ref: ${{ inputs.ebtree_version }}
+        # Relative to Github workspace
+        path: tools/ebtree
+
+    - name: 'Build ebtree ${{ inputs.ebtree_version }}'
+      if: steps.cache-ebtree.outputs.cache-hit != 'true'
+      run: |
+        # fpm is used to build the `.deb` and depends on ruby
+        sudo apt-get update
+        sudo apt-get install -y build-essential ruby ruby-dev
+        sudo gem install --no-document fpm
+        # Build the debian package
+        # Package lives in tools/ebtree/deb/libebtree6[-{dbg,dev}]_$VERSION-distro_arch.deb
+        # $VERSION is ${{ inputs.ebtree_version }} without the leading 'v'
+        # E.g. libebtree6[-{dbg,dev}]_6.0.socio10-bionic_amd64.deb
+        make -C '${{ github.workspace }}/tools/ebtree' deb