diff --git a/repo2docker/buildpacks/conda/__init__.py b/repo2docker/buildpacks/conda/__init__.py
index a46287c5..7271e602 100644
--- a/repo2docker/buildpacks/conda/__init__.py
+++ b/repo2docker/buildpacks/conda/__init__.py
@@ -99,7 +99,7 @@ class CondaBuildPack(BaseImage):
             (
                 "${NB_USER}",
                 r"""
-                npm config --global set prefix ${NPM_DIR}
+                ${NB_PYTHON_PREFIX}/bin/npm config --global set prefix ${NPM_DIR}
                 """,
             ),
         ]