diff --git a/ci-scripts/report-size.sh b/ci-scripts/report-size.sh
index e9c10e9..d85cdbb 100755
--- a/ci-scripts/report-size.sh
+++ b/ci-scripts/report-size.sh
@@ -44,6 +44,7 @@ if [ "$CI" = "true" ]; then
 	curl -o - -v -X 'POST' \
 		"$GITHUB_API_URL/repos/$GITHUB_REPOSITORY/issues/$pr_number/comments?token=$GITHUB_TOKEN" \
 		-H 'accept: application/json' \
+		-H 'Content-Type: application/json' \
 		-d "$data"
 else
 	package_size_table