diff --git a/.github/workflows/TestCITools.yml b/.github/workflows/TestCITools.yml
index 0c71dc7..f5bd710 100644
--- a/.github/workflows/TestCITools.yml
+++ b/.github/workflows/TestCITools.yml
@@ -23,6 +23,7 @@ jobs:
       override_ci_tools_repository: ${{ github.repository }}
       override_ci_tools_ref: ${{ github.sha }}
       extra_toolchains: 'parser_tools;fortran;omp'
+      custom_toolchain_script: true
 
   delta-extension-main:
     name: Rust builds (using Delta extension)
diff --git a/.github/workflows/_extension_distribution.yml b/.github/workflows/_extension_distribution.yml
index edc3395..eb5120a 100644
--- a/.github/workflows/_extension_distribution.yml
+++ b/.github/workflows/_extension_distribution.yml
@@ -76,6 +76,11 @@ on:
         required: false
         type: string
         default: ""
+      # If set, the setup will look for a script in `./scripts/custom-toolchain-script.sh` to run
+      custom_toolchain_script:
+        required: false
+        type: boolean
+        default: false
       # DEPRECATED: use extra_toolchains instead
       enable_rust:
         required: false
@@ -296,6 +301,15 @@ jobs:
           echo "OPENSSL_DIR=`pwd`/build/release/vcpkg_installed/${{ matrix.vcpkg_triplet }}" >> $GITHUB_ENV
           echo "OPENSSL_USE_STATIC_LIBS=true" >> $GITHUB_ENV
 
+      ###
+      # Custom toolchain script
+      ###
+      - name: Run custom toolchain script
+        if: ${{ inputs.custom_toolchain_script }}
+        shell: bash
+        run: |
+          bash scripts/setup-custom-toolchain.sh
+
       ###
       # Building & testing
       ###
@@ -415,6 +429,12 @@ jobs:
           echo "CPPFLAGS=-I/opt/homebrew/opt/libomp/include" >> $GITHUB_ENV
           echo "CXXFLAGS=-I/opt/homebrew/opt/libomp/include" >> $GITHUB_ENV
 
+      - name: Run custom toolchain script
+        if: ${{ inputs.custom_toolchain_script }}
+        shell: bash
+        run: |
+          bash scripts/setup-custom-toolchain.sh
+
       - name: Build extension
         shell: bash
         env:
@@ -519,6 +539,12 @@ jobs:
           vcpkgGitCommitId: ${{ inputs.vcpkg_commit }}
           vcpkgGitURL: ${{ inputs.vcpkg_url }}
 
+      - name: Run custom toolchain script
+        if: ${{ inputs.custom_toolchain_script }}
+        shell: bash
+        run: |
+          bash scripts/setup-custom-toolchain.sh
+
       - name: Build & test extension
         env:
           DUCKDB_PLATFORM: ${{ matrix.duckdb_arch }}
@@ -598,6 +624,12 @@ jobs:
         with:
           key: ${{ github.job }}-${{ matrix.duckdb_arch }}
 
+      - name: Run custom toolchain script
+        if: ${{ inputs.custom_toolchain_script }}
+        shell: bash
+        run: |
+          bash scripts/setup-custom-toolchain.sh
+
       - name: Build Wasm module
         run: |
           make ${{ matrix.duckdb_arch }}