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

*** 335,349 ****
              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);
          return true;
      }
  
      @SuppressWarnings("unchecked")
      public E peek() {
--- 335,346 ----
              throw new NullPointerException();
          modCount++;
          int i = size;
          if (i >= queue.length)
              grow(i + 1);
          siftUp(i, e);
+         size = i + 1;
          return true;
      }
  
      @SuppressWarnings("unchecked")
      public E peek() {