diff --git a/lib/PplBackend/build.sh b/lib/PplBackend/build.sh
index a4358e5ba..aba364d33 100755
--- a/lib/PplBackend/build.sh
+++ b/lib/PplBackend/build.sh
@@ -12,6 +12,7 @@ if [ x${CACHE_PATH} = x ];then
 fi
 
 rm -rf $CACHE_PATH
+rm -rf build
 
 mkdir -p build
 cd build