diff --git a/src/main/java/io/reactivex/disposables/CompositeDisposable.java b/src/main/java/io/reactivex/disposables/CompositeDisposable.java
index 5bed43ec77..a390e1cc1d 100644
--- a/src/main/java/io/reactivex/disposables/CompositeDisposable.java
+++ b/src/main/java/io/reactivex/disposables/CompositeDisposable.java
@@ -93,7 +93,7 @@ public boolean isDisposed() {
      */
     @Override
     public boolean add(@NonNull Disposable d) {
-        ObjectHelper.requireNonNull(d, "d is null");
+        ObjectHelper.requireNonNull(d, "Disposable item is null");
         if (!disposed) {
             synchronized (this) {
                 if (!disposed) {
@@ -128,7 +128,7 @@ public boolean addAll(@NonNull Disposable... ds) {
                         resources = set;
                     }
                     for (Disposable d : ds) {
-                        ObjectHelper.requireNonNull(d, "d is null");
+                        ObjectHelper.requireNonNull(d, "Disposable item is null");
                         set.add(d);
                     }
                     return true;