diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 49d4898976..870d149bbb 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -45,6 +45,7 @@ jobs:
         name: Set up PDM
         with:
           python-version: "3.8"
+          version: "2.20.1"
           allow-python-prereleases: false
           cache: true
           cache-dependency-path: |
@@ -70,6 +71,7 @@ jobs:
         name: Set up PDM
         with:
           python-version: "3.8"
+          version: "2.20.1"
           allow-python-prereleases: false
           cache: true
           cache-dependency-path: |
@@ -95,6 +97,7 @@ jobs:
         name: Set up PDM
         with:
           python-version: "3.8"
+          version: "2.20.1"
           allow-python-prereleases: false
           cache: true
           cache-dependency-path: |
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index f96f85a9ce..1defdae5ed 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -39,6 +39,7 @@ jobs:
         name: Set up PDM
         with:
           python-version: ${{ inputs.python-version }}
+          version: ${{ inputs.python-version == '3.8' && '2.20.1' || ''}}
           allow-python-prereleases: false
           cache: true
           cache-dependency-path: |