diff --git a/.github/workflows/python.yaml b/.github/workflows/python.yaml
index a265340..1fd81b9 100644
--- a/.github/workflows/python.yaml
+++ b/.github/workflows/python.yaml
@@ -31,6 +31,7 @@ jobs:
         shell: bash
         run: |
           set -e
+          pip install --upgrade "pip<20"
           pip install ainu-utils --find-links dist --force-reinstall
           pip install pytest
           cd ./ainu-utils-python && pytest
\ No newline at end of file
diff --git a/.github/workflows/python_release.yaml b/.github/workflows/python_release.yaml
index e55a48f..5e4d7de 100644
--- a/.github/workflows/python_release.yaml
+++ b/.github/workflows/python_release.yaml
@@ -43,6 +43,7 @@ jobs:
         shell: bash
         run: |
           set -e
+          pip install --upgrade "pip<20"
           pip install ainu-utils --find-links dist --force-reinstall
           pip install pytest
           cd ./ainu-utils-python && pytest
@@ -89,6 +90,7 @@ jobs:
         shell: bash
         run: |
           set -e
+          pip install --upgrade "pip<20"
           pip install ainu-utils --find-links dist --force-reinstall
           pip install pytest
           cd ./ainu-utils-python && pytest
@@ -119,6 +121,7 @@ jobs:
         shell: bash
         run: |
           set -e
+          pip install --upgrade "pip<20"
           pip install ainu-utils --find-links dist --force-reinstall
           pip install pytest
           cd ./ainu-utils-python && pytest