diff --git a/docker_test.sh b/docker_test.sh
index 6a1dfcf477b01f5dde465707515128ac58f1934a..bdbb817236e08e4588ecc8036f48cf127c480c93 100755
--- a/docker_test.sh
+++ b/docker_test.sh
@@ -64,7 +64,7 @@ else
   exit 0
 fi
 
-if [[ -d "$1" ]]; then
+if [[ ! -d "$1" ]]; then
   echo "ERROR : directory does not exist ($1)"
   usage
   exit 1