diff --git a/lib/types/message-types.js b/lib/types/message-types.js
--- a/lib/types/message-types.js
+++ b/lib/types/message-types.js
@@ -199,7 +199,7 @@
 export function isMediaMessageType(ourMessageType: MessageType): boolean {
   return mediaMessageTypes.has(ourMessageType);
 }
-export function assetMediaMessageType(
+export function assertMediaMessageType(
   ourMessageType: MessageType,
 ): MessageType {
   invariant(isMediaMessageType(ourMessageType), 'MessageType is not media');