diff --git a/entrypoint.sh b/entrypoint.sh
index e72b3c6..026ea09 100755
--- a/entrypoint.sh
+++ b/entrypoint.sh
@@ -6,4 +6,8 @@ export GITHUB="true"
 
 [ -n "$*" ] && export TELEGRAM_MESSAGE="$*"
 
+# The runner exports every declared input as an env var even when unset,
+# and drone-telegram rejects an empty string for this integer flag.
+[ -z "${INPUT_MESSAGE_THREAD_ID:-}" ] && unset INPUT_MESSAGE_THREAD_ID
+
 /bin/drone-telegram