diff --git a/tensorflow/python/util/tf_export.py b/tensorflow/python/util/tf_export.py
index e4d6bebc3db..04c96d03617 100644
--- a/tensorflow/python/util/tf_export.py
+++ b/tensorflow/python/util/tf_export.py
@@ -341,9 +341,9 @@ class api_export(object):  # pylint: disable=invalid-name
     # their own _tf_api_names as opposed to just inheriting it.
     if api_names_attr in func.__dict__:
       if not self._allow_multiple_exports:
-        # TODO(annarev): temporarily removing check to fix builds.
-        # Need to investigate why symbols get reported multiple times.
-        return
+        raise SymbolAlreadyExposedError(
+            'Symbol %s is already exposed as %s.' %
+            (func.__name__, getattr(func, api_names_attr)))  # pylint: disable=protected-access
     setattr(func, api_names_attr, names)
 
   def export_constant(self, module_name, name):
diff --git a/tensorflow/python/util/tf_export_test.py b/tensorflow/python/util/tf_export_test.py
index 51d9901fdb4..20625792e9b 100644
--- a/tensorflow/python/util/tf_export_test.py
+++ b/tensorflow/python/util/tf_export_test.py
@@ -152,8 +152,7 @@ class ValidateExportTest(test.TestCase):
                        (('NAME_E', 'NAME_F'), 0.5)],
                       module2._tf_api_constants)
 
-  # TODO(b/151745456): re-enable
-  def DISABLED_testRaisesExceptionIfAlreadyHasAPINames(self):
+  def testRaisesExceptionIfAlreadyHasAPINames(self):
     _test_function._tf_api_names = ['abc']
     export_decorator = tf_export.tf_export('nameA', 'nameB')
     with self.assertRaises(tf_export.SymbolAlreadyExposedError):