diff --git a/src/matrix-send-message.js b/src/matrix-send-message.js
index 915b173..784a3a0 100644
--- a/src/matrix-send-message.js
+++ b/src/matrix-send-message.js
@@ -127,7 +127,7 @@ module.exports = function(RED) {
                 }
 
                 if(msgFormat === 'msg.format') {
-                    if(!msg.format) {
+                    if(!Object.keys(msg).includes(format)) {
                         node.error("Message format is set to be passed in via msg.format but was not defined", msg);
                         return;
                     }
@@ -202,4 +202,4 @@ module.exports = function(RED) {
         });
     }
     RED.nodes.registerType("matrix-send-message", MatrixSendImage);
-}
\ No newline at end of file
+}