diff --git a/src/objective-c/RxLibrary/GRXForwardingWriter.m b/src/objective-c/RxLibrary/GRXForwardingWriter.m
index 2342f51ab36..cf8be8c557e 100644
--- a/src/objective-c/RxLibrary/GRXForwardingWriter.m
+++ b/src/objective-c/RxLibrary/GRXForwardingWriter.m
@@ -48,7 +48,10 @@
 // Designated initializer
 - (instancetype)initWithWriter:(GRXWriter *)writer {
   if (!writer) {
-    [NSException raise:NSInvalidArgumentException format:@"writer can't be nil."];
+    return nil;
+  }
+  if (writer.state != GRXWriterStateNotStarted) {
+    [NSException raise:NSInvalidArgumentException format:@"writer can't be started."];
   }
   if ((self = [super init])) {
     _writer = writer;