diff --git a/Lib/multiprocessing/util.py b/Lib/multiprocessing/util.py
index 0c4eb2473273b4..a036d72cc2f60e 100644
--- a/Lib/multiprocessing/util.py
+++ b/Lib/multiprocessing/util.py
@@ -348,8 +348,11 @@ def __exit__(self, *args):
 
 
 class ForkAwareLocal(threading.local):
-    def __init__(self):
-        register_after_fork(self, lambda obj : obj.__dict__.clear())
+    def __new__(cls):
+        self = threading.local.__new__(cls)
+        register_after_fork(self, lambda obj: obj.__dict__.clear())
+        return self
+
     def __reduce__(self):
         return type(self), ()
 
diff --git a/Lib/test/_test_multiprocessing.py b/Lib/test/_test_multiprocessing.py
index f4239badfe8b7e..fcdf9f4d97081a 100644
--- a/Lib/test/_test_multiprocessing.py
+++ b/Lib/test/_test_multiprocessing.py
@@ -4598,6 +4598,27 @@ def test_lock(self):
         join_process(p)
         self.assertLessEqual(new_size, old_size)
 
+#
+# Issue #26180: ForkAwareLocal
+#
+
+class TestForkAwareLocal(unittest.TestCase):
+    # Issue #26180 meant that with each new thread using an instance of
+    # ForkAwareLocal, fork registry would get a duplicate entry for that
+    # instance.
+
+    def test_registry_after_thread_spawn(self):
+        v = util.ForkAwareLocal()
+        # v cleanup handler is now registered.
+        old_size = len(util._afterfork_registry)
+        # Setting an attr on v from a new thread will call v.__init__.
+        t = threading.Thread(target=setattr, args=(v, 'x', 0))
+        t.start()
+        t.join()
+        # Ensure that v.__init__ did not register a new handler.
+        new_size = len(util._afterfork_registry)
+        self.assertEqual(new_size, old_size)
+
 #
 # Check that non-forked child processes do not inherit unneeded fds/handles
 #
diff --git a/Misc/NEWS.d/next/Library/2019-06-11-22-58-11.bpo-26180.yXZmdk.rst b/Misc/NEWS.d/next/Library/2019-06-11-22-58-11.bpo-26180.yXZmdk.rst
new file mode 100644
index 00000000000000..9b59fd9a13bc12
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-06-11-22-58-11.bpo-26180.yXZmdk.rst
@@ -0,0 +1,2 @@
+Fixed memory leak in :class:`multiprocessing.util.ForkAwareLocal` when used
+by multiple threads.