diff --git a/lib/configuration.sh b/lib/configuration.sh
index 8bf788be6a..0b337aa419 100644
--- a/lib/configuration.sh
+++ b/lib/configuration.sh
@@ -61,8 +61,10 @@ fi
 [[ $ROOTFS_TYPE == nfs ]] && FIXED_IMAGE_SIZE=64
 
 # used by multiple sources - reduce code duplication
-if [[ $USE_MAINLINE_GOOGLE_MIRROR == yes ]]; then
+if [[ $MAINLINE_MIRROR == 'google' ]]; then
 	MAINLINE_KERNEL_SOURCE='https://kernel.googlesource.com/pub/scm/linux/kernel/git/stable/linux-stable'
+elif [[ $MAINLINE_MIRROR == 'tuna' ]]; then
+	MAINLINE_KERNEL_SOURCE='https://mirrors.tuna.tsinghua.edu.cn/git/linux-stable.git'
 else
 	MAINLINE_KERNEL_SOURCE='git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git'
 fi