diff --git a/ci/test/01_base_install.sh b/ci/test/01_base_install.sh
index 0ac56208f9b..3e0bc4666ef 100755
--- a/ci/test/01_base_install.sh
+++ b/ci/test/01_base_install.sh
@@ -22,6 +22,11 @@ if [ -n "$DPKG_ADD_ARCH" ]; then
 fi
 
 if [ -n "${APT_LLVM_V}" ]; then
+  # Temporarily work around Sequoia PGP policy deadline for legacy repositories.
+  # See https://github.com/llvm/llvm-project/issues/153385.
+  if [ -f /usr/share/apt/default-sequoia.config ]; then
+    sed -i 's/\(sha1\.second_preimage_resistance =\).*/\1 9999-01-01/' /usr/share/apt/default-sequoia.config
+  fi
   ${CI_RETRY_EXE} apt-get update
   ${CI_RETRY_EXE} apt-get install curl -y
   curl "https://apt.llvm.org/llvm-snapshot.gpg.key" | tee "/etc/apt/trusted.gpg.d/apt.llvm.org.asc"