diff --git a/ci/build.sh b/ci/build.sh
index 70ca459..9359ca6 100755
--- a/ci/build.sh
+++ b/ci/build.sh
@@ -40,6 +40,9 @@
       echo "-s DIR      SDK cache dir (must exist)."
       echo "-S          Build SDK only"
       echo "-c          Container to run in"
+      echo ""
+      echo "Note: set environment variables HTTP_PROXY and HTTPS_PROXY if a proxy is required."
+      echo ""
       echo "Example:DOCKER_PREFIX=sudo ./ci/build.sh -a"
       echo -e "\tDOCKER_PREFIX=sudo ./ci/build.sh -p firestone"
       echo -e "\tDOCKER_PREFIX=sudo ./ci/build.sh -p garrison,palmetto,openpower_p9_mambo"