diff --git a/Lib/numbers.py b/Lib/numbers.py
index fa59fd8..540e7d5 100644
--- a/Lib/numbers.py
+++ b/Lib/numbers.py
@@ -17,6 +17,7 @@
     caring what kind, use isinstance(x, Number).
     """
     __metaclass__ = ABCMeta
+    __slots__ = ()
 
     # Concrete numeric types must provide their own hash implementation
     __hash__ = None
@@ -41,6 +42,8 @@
     type as described below.
     """
 
+    __slots__ = ()
+
     @abstractmethod
     def __complex__(self):
         """Return a builtin complex instance. Called for complex(self)."""
@@ -172,6 +175,8 @@
     Real also provides defaults for the derived operations.
     """
 
+    __slots__ = ()
+
     @abstractmethod
     def __float__(self):
         """Any Real can be converted to a native float object.
@@ -265,6 +270,8 @@
 class Rational(Real):
     """.numerator and .denominator should be in lowest terms."""
 
+    __slots__ = ()
+
     @abstractproperty
     def numerator(self):
         raise NotImplementedError
@@ -288,6 +295,8 @@
 class Integral(Rational):
     """Integral adds a conversion to long and the bit-string operations."""
 
+    __slots__ = ()
+
     @abstractmethod
     def __long__(self):
         """long(self)"""
diff --git a/Lib/test/test_fractions.py b/Lib/test/test_fractions.py
index a6c3c32..0509f92 100644
--- a/Lib/test/test_fractions.py
+++ b/Lib/test/test_fractions.py
@@ -394,6 +394,11 @@
         self.assertEqual(id(r), id(copy(r)))
         self.assertEqual(id(r), id(deepcopy(r)))
 
+    def test_slots(self):
+        # Issue 4998
+        r = F(13, 7)
+        self.assertRaises(AttributeError, setattr, r, 'a', 10)
+
 def test_main():
     run_unittest(FractionTest, GcdTest)
 
diff --git a/Misc/NEWS b/Misc/NEWS
index 9176b6c..de3f6be 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -80,6 +80,10 @@
 Library
 -------
 
+- Issue #4998: The memory saving effect of __slots__ had been lost on Fractions
+  which inherited from numbers.py which did not have __slots__ defined.  The
+  numbers hierarchy now has its own __slots__ declarations.
+
 - Issue #5203: Fixed ctypes segfaults when passing a unicode string to a
   function without argtypes (only occurs if HAVE_USABLE_WCHAR_T is false).