diff --git a/packages/grpc-native-core/index.d.ts b/packages/grpc-native-core/index.d.ts
index 4ffa5993..ac11056e 100644
--- a/packages/grpc-native-core/index.d.ts
+++ b/packages/grpc-native-core/index.d.ts
@@ -794,7 +794,13 @@ declare module "grpc" {
     ERROR,
   }
 
+  /**
+   * A certificate as received by the checkServerIdentity callback.
+   */
   export interface Certificate {
+    /**
+     * The raw certificate in DER form.
+     */
     raw: Buffer;
   }