diff --git a/elements/rocky-container-stackhpc/containerfiles/9-stackhpc b/elements/rocky-container-stackhpc/containerfiles/9-stackhpc
index 8d3d831..a757036 100644
--- a/elements/rocky-container-stackhpc/containerfiles/9-stackhpc
+++ b/elements/rocky-container-stackhpc/containerfiles/9-stackhpc
@@ -18,6 +18,15 @@ RUN if [[ ${ROCKY_USE_CUSTOM_DNF_MIRRORS} != "false" ]]; then \
 RUN dnf group install -y 'Minimal Install' --allowerasing && \
     dnf install -y findutils util-linux cloud-init
 
+# Repositories need to be disabled a second time to downgrade kernel.
+RUN if [[ ${ROCKY_USE_CUSTOM_DNF_MIRRORS} != "false" ]]; then \
+      dnf config-manager --disable \* && \
+      for REPO_URL in $(echo ${ROCKY_CUSTOM_DNF_MIRROR_URLS} | sed 's/,/ /g'); do \
+        dnf config-manager --add-repo ${REPO_URL}; \
+      done && \
+      dnf --allowerasing -y distro-sync; \
+    fi
+
 COPY <<EOF /etc/cloud/cloud.cfg.d/10-NetworkManager.cfg
 ---
 system_info: