diff --git a/db-migration-worker/Dockerfile b/db-migration-worker/Dockerfile
index 139b3403a..92dff618f 100644
--- a/db-migration-worker/Dockerfile
+++ b/db-migration-worker/Dockerfile
@@ -1,7 +1,9 @@
-FROM mongo:latest
+FROM mongo:4
 
-RUN apt-get update
-RUN apt-get -y install openssh-client
+RUN apt-get update \
+ && apt-get -y install --no-install-recommends openssh-client \
+ && apt-get clean \
+ && rm -rf /var/lib/apt/lists/*
 COPY .ssh /root/.ssh/
 COPY import.sh .
 
diff --git a/db-migration-worker/import.sh b/db-migration-worker/import.sh
index b1042844b..ba07217c0 100755
--- a/db-migration-worker/import.sh
+++ b/db-migration-worker/import.sh
@@ -4,7 +4,7 @@ for var in "SSH_USERNAME" "SSH_HOST" "MONGODB_USERNAME" "MONGODB_PASSWORD" "MONG
 do
   if [[ -z "${!var}" ]]; then
     echo "${var} is undefined"
-    exit -1
+    exit 1
   fi
 done