diff --git a/benchmark/cpp-test.sh b/benchmark/cpp-test.sh
index 6e9de9a8f..519e9d61a 100755
--- a/benchmark/cpp-test.sh
+++ b/benchmark/cpp-test.sh
@@ -3,7 +3,7 @@
 # exit when any command fails
 set -e
 
-mkdir build
+[ ! -d "build" ] && mkdir build
 cd build
 cmake -G "Unix Makefiles" ..
 make