diff --git a/stub/src/main/java/io/grpc/stub/MetadataUtils.java b/stub/src/main/java/io/grpc/stub/MetadataUtils.java
index ad23e4ef44..609df039ab 100644
--- a/stub/src/main/java/io/grpc/stub/MetadataUtils.java
+++ b/stub/src/main/java/io/grpc/stub/MetadataUtils.java
@@ -65,7 +65,7 @@ public final class MetadataUtils {
 
     // Non private to avoid synthetic class
     HeaderAttachingClientInterceptor(Metadata extraHeaders) {
-      this.extraHeaders = checkNotNull(extraHeaders, extraHeaders);
+      this.extraHeaders = checkNotNull(extraHeaders, "extraHeaders");
     }
 
     @Override