diff --git a/get-modified-image.sh b/get-modified-image.sh
index 714b2fed116653596effdeb6f772aba8eff96d4c..23bf3d3e9e82ecd396d6cd3554ca38bcd9cbe968 100755
--- a/get-modified-image.sh
+++ b/get-modified-image.sh
@@ -15,12 +15,15 @@ do
   esac
 done
 echo "export MODIFIED_IMAGE=${RES}" > variables
+echo "Using modified folder : $RES"
 
 # Image name with wanted registry and tag, fetched from Docker Compose
 RES=$(cat $RES/docker-compose.yml | grep $RES: | cut -d ':' -f2- | cut -d '/' -f2- | tr -d ' ')
-if [ "$RES" = "" ]; then exit 1; fi
+if [ "$RES" = "" ]; then
+  echo "Error : no reference to $RES found in docker-compose.yml."
+  echo "Please check the repository README : the name of the folder must be the same as name of the image."
+  exit 1
+fi
 
 echo "export MODIFIED_IMAGE_FULL_TEST=registry.test.picasoft.net/${RES}" >> variables
 echo "export MODIFIED_IMAGE_FULL=registry.picasoft.net/${RES}" >> variables
-
-echo "Found modified folder : $RES"