src/java.base/share/classes/java/util/PriorityQueue.java

@@ -335,15 +335,12 @@
             throw new NullPointerException();
         modCount++;
         int i = size;
         if (i >= queue.length)
             grow(i + 1);
-        size = i + 1;
-        if (i == 0)
-            queue[0] = e;
-        else
             siftUp(i, e);
+        size = i + 1;
         return true;
     }
 
     @SuppressWarnings("unchecked")
     public E peek() {