diff --git a/paddle/scripts/docker/build.sh b/paddle/scripts/docker/build.sh
index 1ccee686df4faa930dcaba0d38f7571c9aaadd4a..ab60f1a38dd4cd1d9799c0019dccae5f1c7d4310 100644
--- a/paddle/scripts/docker/build.sh
+++ b/paddle/scripts/docker/build.sh
@@ -78,7 +78,7 @@ paddle version
 # PaddlePaddle.  This awkwardness is due to
 # https://github.com/PaddlePaddle/Paddle/issues/1854.  It also
 # describes a solution.
-if [ ${WITH_DOC} == "ON" ]; then
+if [[ ${WITH_DOC} == "ON" ]]; then
     cat <<EOF
 ========================================
 Building documentation ...