diff --git a/Lib/ipaddress.py b/Lib/ipaddress.py
index d15a1d9..b32a7e1 100644
--- a/Lib/ipaddress.py
+++ b/Lib/ipaddress.py
@@ -808,7 +808,7 @@
                 other.broadcast_address <= self.broadcast_address):
             raise ValueError('%s not contained in %s' % (other, self))
         if other == self:
-            raise StopIteration
+            return
 
         # Make sure we're comparing the network of other.
         other = other.__class__('%s/%s' % (other.network_address,
diff --git a/Lib/mailbox.py b/Lib/mailbox.py
index 145b204..e7f31df 100644
--- a/Lib/mailbox.py
+++ b/Lib/mailbox.py
@@ -1949,7 +1949,7 @@
         while True:
             line = self.readline()
             if not line:
-                raise StopIteration
+                return
             yield line
 
     def tell(self):
diff --git a/Lib/test/test_buffer.py b/Lib/test/test_buffer.py
index 1667847..1cdc771 100644
--- a/Lib/test/test_buffer.py
+++ b/Lib/test/test_buffer.py
@@ -216,7 +216,7 @@
     for t in iter_mode(nitems, testobj):
         yield t
     if testobj != 'ndarray':
-        raise StopIteration
+        return
     yield struct_items(nitems, testobj)
 
 
diff --git a/Lib/test/test_collections.py b/Lib/test/test_collections.py
index e948106..7b46475 100644
--- a/Lib/test/test_collections.py
+++ b/Lib/test/test_collections.py
@@ -511,7 +511,7 @@
         class NextOnly:
             def __next__(self):
                 yield 1
-                raise StopIteration
+                return
         self.assertNotIsInstance(NextOnly(), Iterator)
 
     def test_Sized(self):
diff --git a/Lib/test/test_itertools.py b/Lib/test/test_itertools.py
index 5f33d39..d48bf55 100644
--- a/Lib/test/test_itertools.py
+++ b/Lib/test/test_itertools.py
@@ -1803,8 +1803,6 @@
             hist.append(3)
             yield 2
             hist.append(4)
-            if x:
-                raise StopIteration
 
         hist = []
         self.assertRaises(AssertionError, list, chain(gen1(), gen2(False)))
diff --git a/Lib/test/test_sys_setprofile.py b/Lib/test/test_sys_setprofile.py
index 9816e3e..e59320b 100644
--- a/Lib/test/test_sys_setprofile.py
+++ b/Lib/test/test_sys_setprofile.py
@@ -260,7 +260,6 @@
         def f():
             for i in range(2):
                 yield i
-            raise StopIteration
         def g(p):
             for i in f():
                 pass