diff --git a/src/objective-c/GRPCClient/GRPCCall.h b/src/objective-c/GRPCClient/GRPCCall.h
index 2495aface69..496242a1b6f 100644
--- a/src/objective-c/GRPCClient/GRPCCall.h
+++ b/src/objective-c/GRPCClient/GRPCCall.h
@@ -165,6 +165,7 @@ extern id const kGRPCTrailersKey;
 
 /**
  * The server name for the RPC. If nil, the host name of the service object will be used instead.
+ * This property must be nil when Cronet transport is enabled.
  */
 @property (atomic, readwrite) NSString *serverName;