diff --git a/src/objective-c/GRPCClient/GRPCCallOptions.h b/src/objective-c/GRPCClient/GRPCCallOptions.h
index 68d3eb4fbb3..ff575d09cf8 100644
--- a/src/objective-c/GRPCClient/GRPCCallOptions.h
+++ b/src/objective-c/GRPCClient/GRPCCallOptions.h
@@ -226,7 +226,7 @@ typedef NS_ENUM(NSInteger, GRPCTransportType) {
 /**
  * Initial metadata key-value pairs that should be included in the request.
  */
-@property(copy, readonly) NSDictionary *initialMetadata;
+@property(copy, readwrite) NSDictionary *initialMetadata;
 
 // Channel parameters; take into account of channel signature.