diff --git a/libraries/GCS_MAVLink/GCS_Signing.cpp b/libraries/GCS_MAVLink/GCS_Signing.cpp
index 5d0023c369..163147561c 100644
--- a/libraries/GCS_MAVLink/GCS_Signing.cpp
+++ b/libraries/GCS_MAVLink/GCS_Signing.cpp
@@ -145,6 +145,7 @@ void GCS_MAVLINK::load_signing_key(void)
     for (uint8_t i=0; i<sizeof(key.secret_key); i++) {
         if (signing.secret_key[i] != 0) {
             all_zero = false;
+            break;
         }
     }