diff --git a/.github/workflows/phono3py-pytest-conda.yml b/.github/workflows/phono3py-pytest-conda.yml
index 1df4515a..7ae69ede 100644
--- a/.github/workflows/phono3py-pytest-conda.yml
+++ b/.github/workflows/phono3py-pytest-conda.yml
@@ -24,7 +24,7 @@ jobs:
       run: |
         conda activate test
         conda install --yes python=${{ matrix.python-version }}
-        conda install --yes matplotlib-base pyyaml "libblas=*=*openblas" openblas h5py scipy pytest spglib alm cmake c-compiler cxx-compiler
+        conda install --yes matplotlib-base pyyaml "libblas=*=*openblas" openblas h5py scipy pytest spglib alm cmake c-compiler cxx-compiler pypolymlp
     - name: Install phonopy develop branch
       run: |
         conda activate test