diff --git a/packages/proto-signing/src/registry.ts b/packages/proto-signing/src/registry.ts
index 0e43a08c..e75ffdbd 100644
--- a/packages/proto-signing/src/registry.ts
+++ b/packages/proto-signing/src/registry.ts
@@ -10,7 +10,8 @@ import type protobuf from "protobufjs";
  * A type generated by Telescope 1.0.
  */
 export interface TelescopeGeneratedType {
-  readonly typeUrl: string;
+  /** This may or may not exist depending on the code generator settings. Don't rely on it. */
+  readonly typeUrl?: string;
   readonly encode: (
     message:
       | any