diff --git a/.github/workflows/dotnet-build-and-test.yml b/.github/workflows/dotnet-build-and-test.yml
index 2d079f488e..5fe8e5ba77 100644
--- a/.github/workflows/dotnet-build-and-test.yml
+++ b/.github/workflows/dotnet-build-and-test.yml
@@ -48,9 +48,13 @@ jobs:
       - uses: actions/checkout@v6
         with:
           ref: ${{ inputs.checkout-ref }}
+      - name: Fetch base branch for comparison
+        if: ${{ inputs.checkout-ref != '' }}
+        run: git fetch origin main --depth=1
       - uses: dorny/paths-filter@v3
         id: filter
         with:
+          base: ${{ inputs.checkout-ref != '' && 'main' || '' }}
           filters: |
             dotnet:
               - 'dotnet/**'
diff --git a/.github/workflows/python-merge-tests.yml b/.github/workflows/python-merge-tests.yml
index 57241c4253..4db9001bc8 100644
--- a/.github/workflows/python-merge-tests.yml
+++ b/.github/workflows/python-merge-tests.yml
@@ -38,9 +38,13 @@ jobs:
       - uses: actions/checkout@v6
         with:
           ref: ${{ inputs.checkout-ref }}
+      - name: Fetch base branch for comparison
+        if: ${{ inputs.checkout-ref != '' }}
+        run: git fetch origin main --depth=1
       - uses: dorny/paths-filter@v3
         id: filter
         with:
+          base: ${{ inputs.checkout-ref != '' && 'main' || '' }}
           filters: |
             python:
               - 'python/**'