diff --git a/base-notebook/Dockerfile b/base-notebook/Dockerfile
index d43d830b..72b90a95 100644
--- a/base-notebook/Dockerfile
+++ b/base-notebook/Dockerfile
@@ -86,8 +86,6 @@ USER ${NB_UID}
 
 # Pin versions here, or set them to "default"
 ARG PYTHON_VERSION=3.9
-ARG MAMBA_VERSION=default
-ARG MICROMAMBA_VERSION=default
 
 # Setup work directory for backward-compatibility
 RUN mkdir "/home/${NB_USER}/work" && \
@@ -112,15 +110,11 @@ RUN set -x && \
         # Should be simpler, see <https://github.com/mamba-org/mamba/issues/1437>
         arch="64"; \
     fi && \
-    if [[ "${MICROMAMBA_VERSION}" == "default" ]]; then MICROMAMBA_VERSION="latest"; fi && \
     wget -qO /tmp/micromamba.tar.bz2 \
-        "https://micromamba.snakepit.net/api/micromamba/linux-${arch}/${MICROMAMBA_VERSION}" && \
+        "https://micromamba.snakepit.net/api/micromamba/linux-${arch}/latest" && \
     tar -xvjf /tmp/micromamba.tar.bz2 --strip-components=1 bin/micromamba && \
     rm /tmp/micromamba.tar.bz2 && \
     PYTHON_SPECIFIER="python=${PYTHON_VERSION}" && \
-    if [[ "${PYTHON_VERSION}" == "default" ]]; then PYTHON_SPECIFIER="python"; fi && \
-    MAMBA_SPECIFIER="mamba=${MAMBA_VERSION}" && \
-    if [[ "${MAMBA_VERSION}" == "default" ]]; then MAMBA_SPECIFIER="mamba"; fi && \
     if [ "${arch}" == "aarch64" ]; then \
         # Prevent libmamba from sporadically hanging on arm64 under QEMU
         # <https://github.com/mamba-org/mamba/issues/1611>
@@ -132,7 +126,7 @@ RUN set -x && \
         --prefix="${CONDA_DIR}" \
         --yes \
         "${PYTHON_SPECIFIER}" \
-        "${MAMBA_SPECIFIER}" \
+        'mamba' \
         'notebook' \
         'jupyterhub' \
         'jupyterlab' && \