diff --git a/.github/workflows/build_deb_package.yml b/.github/workflows/build_deb_package.yml
index 79664648ab..04d43f7224 100644
--- a/.github/workflows/build_deb_package.yml
+++ b/.github/workflows/build_deb_package.yml
@@ -90,6 +90,17 @@ jobs:
 
       - name: Fix git in container
         run: |
+          # Switch to AWS regional mirrors. runs-on instances are in us-west-2,
+          # and the EC2 archive mirrors are Canonical-operated, region-local,
+          # and sync aggressively. The default archive.ubuntu.com round-robin
+          # sometimes serves out-of-sync index files mid-sync, breaking
+          # apt-get update.
+          if [ -f /etc/apt/sources.list.d/ubuntu.sources ]; then
+            sed -i 's|http://archive.ubuntu.com/ubuntu|http://us-west-2.ec2.archive.ubuntu.com/ubuntu|g; s|http://security.ubuntu.com/ubuntu|http://us-west-2.ec2.archive.ubuntu.com/ubuntu|g' /etc/apt/sources.list.d/ubuntu.sources
+          fi
+          if [ -f /etc/apt/sources.list ]; then
+            sed -i 's|http://archive.ubuntu.com/ubuntu|http://us-west-2.ec2.archive.ubuntu.com/ubuntu|g; s|http://security.ubuntu.com/ubuntu|http://us-west-2.ec2.archive.ubuntu.com/ubuntu|g' /etc/apt/sources.list
+          fi
           apt-get update && apt-get install -y git
           git config --global --add safe.directory $(realpath .)