diff --git a/.github/workflows/main.yaml b/.github/workflows/main.yaml
index 13ee2e27a1..9145a6ccb5 100644
--- a/.github/workflows/main.yaml
+++ b/.github/workflows/main.yaml
@@ -36,7 +36,7 @@ jobs:
   ubuntu:
     name: Build and test AMD64 Ubuntu ${{ matrix.ubuntu }}
     runs-on: ubuntu-${{ matrix.ubuntu }}
-    timeout-minutes: 90
+    timeout-minutes: 60
     strategy:
       fail-fast: false
       matrix:
diff --git a/build/README.md b/build/README.md
index 51e1c09b3b..ed13d10b39 100644
--- a/build/README.md
+++ b/build/README.md
@@ -66,7 +66,7 @@ The following scripts are found in the [`build/`](.) directory. Note that all sc
   * `build/builder.sh make unittest`: Run all unit tests.
   * `build/builder.sh make clean`: Clean up all the generated files.
 
-You can specify different OS for builder by setting `OS_NAME` which defaults to `ubuntu18.04`. Valid OS are `ubuntu18.04`, `centos7`.
+You can specify different OS for builder by setting `OS_NAME` which defaults to `ubuntu20.04`. Valid OS are `ubuntu20.04`,`ubuntu18.04`, `centos7`.
 
 To specify `centos7` builder, use these commands: