diff --git a/Chapter07/heap.py b/Chapter07/heap.py
index ee0aa33..c948f6c 100644
--- a/Chapter07/heap.py
+++ b/Chapter07/heap.py
@@ -5,8 +5,9 @@ def __init__(self):
 
     def arrange(self, k):
         while k // 2 > 0:
-            if self.heap[k] < self.heap[k//2]:
-                self.heap[k], self.heap[k//2] = self.heap[k//2], self.heap[k]
+            if self.heap[k] > self.heap[k//2]:
+                break
+            self.heap[k], self.heap[k//2] = self.heap[k//2], self.heap[k]
             k //= 2
 
     def insert(self, item):
@@ -17,8 +18,9 @@ def insert(self, item):
     def sink(self, k):
         while k * 2 <= self.size:
             mc = self.minchild(k)
-            if self.heap[k] > self.heap[mc]:
-                self.heap[k], self.heap[mc] = self.heap[mc], self.heap[k]
+            if self.heap[k] < self.heap[mc]:
+                break
+            self.heap[k], self.heap[mc] = self.heap[mc], self.heap[k]
             k = mc
 
     def minchild(self, k):
@@ -43,6 +45,7 @@ def delete_at_location(self, location):
         self.heap[location] = self.heap[self.size]
         self.size -= 1
         self.heap.pop()
+        self.arrange(location)
         self.sink(location)
         return item