diff --git a/entrypoint.sh b/entrypoint.sh
index 0b7b7e84a..efd7062f8 100755
--- a/entrypoint.sh
+++ b/entrypoint.sh
@@ -2,21 +2,21 @@
 
 set -e
 
-if [[ -z "$GITHUB_TOKEN" ]]; then
+if [ -z "$GITHUB_TOKEN" ]; then
   echo "Set the GITHUB_TOKEN environment variable."
   exit 1
 fi
 
-if [[ ! -z "$SSH_PRIVATE_KEY" ]]; then
+if [ ! -z "$SSH_PRIVATE_KEY" ]; then
   echo "Saving SSH_PRIVATE_KEY"
 
-  mkdir --parents /root/.ssh
+  mkdir -p /root/.ssh
   echo "$SSH_PRIVATE_KEY" > /root/.ssh/id_rsa
   chmod 600 /root/.ssh/id_rsa
 
   # Github action changes $HOME to /github at runtime
   # therefore we always copy the SSH key to $HOME (aka. ~)
-  mkdir --parents ~/.ssh
+  mkdir -p ~/.ssh
   cp /root/.ssh/* ~/.ssh/ 2> /dev/null || true 
 fi
 
diff --git a/github-sync.sh b/github-sync.sh
index 845013dcf..54b19f5aa 100755
--- a/github-sync.sh
+++ b/github-sync.sh
@@ -5,17 +5,17 @@ set -e
 UPSTREAM_REPO=$1
 BRANCH_MAPPING=$2
 
-if [[ -z "$UPSTREAM_REPO" ]]; then
+if [ -z "$UPSTREAM_REPO" ]; then
   echo "Missing \$UPSTREAM_REPO"
   exit 1
 fi
 
-if [[ -z "$BRANCH_MAPPING" ]]; then
+if [ -z "$BRANCH_MAPPING" ]; then
   echo "Missing \$SOURCE_BRANCH:\$DESTINATION_BRANCH"
   exit 1
 fi
 
-if ! echo $UPSTREAM_REPO | grep -Eq ':|@|\.git\/?$'
+if ! echo "$UPSTREAM_REPO" | grep -Eq ':|@|\.git\/?$'
 then
   echo "UPSTREAM_REPO does not seem to be a valid git URI, assuming it's a GitHub repo"
   echo "Originally: $UPSTREAM_REPO"
@@ -41,14 +41,14 @@ git remote --verbose
 echo "Pushing changings from tmp_upstream to origin"
 git push origin "refs/remotes/tmp_upstream/${BRANCH_MAPPING%%:*}:refs/heads/${BRANCH_MAPPING#*:}" --force
 
-if [[ "$SYNC_TAGS" = true ]]; then
+if [ "$SYNC_TAGS" = true ]; then
   echo "Force syncing all tags"
-  git tag -d $(git tag -l) > /dev/null
+  git tag -d "$(git tag -l)" > /dev/null
   git fetch tmp_upstream --tags --quiet
   git push origin --tags --force
-elif [[ -n "$SYNC_TAGS" ]]; then
+elif [ -n "$SYNC_TAGS" ]; then
   echo "Force syncing tags matching pattern: $SYNC_TAGS"
-  git tag -d $(git tag -l) > /dev/null
+  git tag -d "$(git tag -l)" > /dev/null
   git fetch tmp_upstream --tags --quiet
   git tag | grep "$SYNC_TAGS" | xargs --no-run-if-empty git push origin --force
 fi