diff --git a/repo2docker/buildpacks/conda/__init__.py b/repo2docker/buildpacks/conda/__init__.py
index ff9d9d96..147fc4b8 100644
--- a/repo2docker/buildpacks/conda/__init__.py
+++ b/repo2docker/buildpacks/conda/__init__.py
@@ -339,7 +339,7 @@ class CondaBuildPack(BaseImage):
                     "${NB_USER}",
                     r"""
                 TIMEFORMAT='time: %3R' \
-                bash -c 'time /tmp/bin/micromamba env update -p {0} -f "{1}" && \
+                bash -c 'time /tmp/bin/micromamba update -p {0} -f "{1}" && \
                 # time /tmp/bin/micromamba clean --all -y && \
                 /tmp/bin/micromamba list -p {0} \
                 '
diff --git a/repo2docker/buildpacks/conda/install-base-env.bash b/repo2docker/buildpacks/conda/install-base-env.bash
index e2b17f3e..f68628ce 100755
--- a/repo2docker/buildpacks/conda/install-base-env.bash
+++ b/repo2docker/buildpacks/conda/install-base-env.bash
@@ -6,15 +6,15 @@ set -ex
 
 cd $(dirname $0)
 
-URL="https://anaconda.org/conda-forge/micromamba/0.13.1/download/linux-64/micromamba-0.13.1-0.tar.bz2"
+URL="https://github.com/mamba-org/boa-forge/releases/download/micromamba-nightly-21.5.31.1722/micromamba-nightly-linux-64"
 
 # make sure we don't do anything funky with user's $HOME
 # since this is run as root
 unset HOME
-
 mkdir -p ${CONDA_DIR}
 
-time wget -qO- ${URL} | tar -xvj bin/micromamba
+time wget ${URL} && mkdir bin && mv micromamba-nightly-linux-64 bin/micromamba
+chmod +x bin/micromamba
 
 export MAMBA_ROOT_PREFIX=${CONDA_DIR}
 export MAMBA_EXE="/tmp/bin/micromamba"
diff --git a/tests/conda/binder-dir/verify b/tests/conda/binder-dir/verify
index 3103ceaa..8741a7c5 100755
--- a/tests/conda/binder-dir/verify
+++ b/tests/conda/binder-dir/verify
@@ -5,6 +5,6 @@ from subprocess import check_output
 assert sys.version_info[:2] == (3, 5), sys.version
 
 out = check_output(["/tmp/bin/micromamba", "--version"]).decode("utf8").strip()
-assert out == "0.13.1", out
+assert out == "21.5.31.1722", out
 
 import numpy