diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 4accfa4..375cc12 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -72,7 +72,9 @@ jobs:
 
         python -m pip install --upgrade pip
 
-        pip install pdm
+        # pin packaging to 21.3 for now to prevent: packaging.specifiers.InvalidSpecifier: Invalid specifier: '>=3.4.*'
+        # see https://github.com/pdm-project/pdm/issues/1556
+        pip install --upgrade pdm packaging==21.3
 
         pdm install -v
 
diff --git a/.github/workflows/codeql-analysis.yml b/.github/workflows/codeql-analysis.yml
index 22ddc95..d51f9a6 100644
--- a/.github/workflows/codeql-analysis.yml
+++ b/.github/workflows/codeql-analysis.yml
@@ -49,7 +49,9 @@ jobs:
 
         python -m pip install --upgrade pip
 
-        pip install pdm
+        # pin packaging to 21.3 for now to prevent: packaging.specifiers.InvalidSpecifier: Invalid specifier: '>=3.4.*'
+        # see https://github.com/pdm-project/pdm/issues/1556
+        pip install --upgrade pdm packaging==21.3
 
         # don't install dependencies for now, as this makes CodeQL run forever
         # pdm install -v
diff --git a/.github/workflows/update-python-deps.yml b/.github/workflows/update-python-deps.yml
index 3d6d31d..cf1453e 100644
--- a/.github/workflows/update-python-deps.yml
+++ b/.github/workflows/update-python-deps.yml
@@ -51,10 +51,11 @@ jobs:
 
         python --version
 
-        # don't upgrade PIP for now: https://github.com/pdm-project/pdm/issues/874
-        # python -m pip install --upgrade pip
+        python -m pip install --upgrade pip
 
-        pip install pdm
+        # pin packaging to 21.3 for now to prevent: packaging.specifiers.InvalidSpecifier: Invalid specifier: '>=3.4.*'
+        # see https://github.com/pdm-project/pdm/issues/1556
+        pip install --upgrade pdm packaging==21.3
 
         # https://github.com/pdm-project/pdm/issues/728#issuecomment-1021771200
         pip install -t __pypackages__/${{ env.PYTHON_VERSION }}/lib selenium