diff --git a/octodns/manager.py b/octodns/manager.py
index 89db845..3984a5a 100644
--- a/octodns/manager.py
+++ b/octodns/manager.py
@@ -275,10 +275,13 @@ class Manager(object):
             self.log.info('sync:   sources=%s -> targets=%s', sources, targets)
 
             try:
-                sources = [self.providers[source] for source in sources]
-            except KeyError as e:
+                collected = []
+                for source in sources:
+                    collected.append(self.providers[source])
+                sources = collected
+            except KeyError:
                 raise Exception('Zone {}, unknown source: {}'.format(zone_name,
-                                                                     e))
+                                                                     source))
 
             try:
                 trgs = []
@@ -396,10 +399,13 @@ class Manager(object):
                 raise Exception('Zone {} is missing sources'.format(zone_name))
 
             try:
-                sources = [self.providers[source] for source in sources]
-            except KeyError as e:
+                collected = []
+                for source in sources:
+                    collected.append(self.providers[source])
+                sources = collected
+            except KeyError:
                 raise Exception('Zone {}, unknown source: {}'.format(zone_name,
-                                                                     e))
+                                                                     source))
 
             for source in sources:
                 if isinstance(source, YamlProvider):
diff --git a/octodns/provider/route53.py b/octodns/provider/route53.py
index 7154096..d72b384 100644
--- a/octodns/provider/route53.py
+++ b/octodns/provider/route53.py
@@ -20,6 +20,7 @@ from ..record import Record, Update
 from ..record.geo import GeoCodes
 from .base import BaseProvider
 
+# TODO: remove when Python 2.x is no longer supported
 try:
     cmp
 except NameError:
diff --git a/octodns/record/__init__.py b/octodns/record/__init__.py
index 2efdf0e..82b1400 100644
--- a/octodns/record/__init__.py
+++ b/octodns/record/__init__.py
@@ -13,6 +13,7 @@ from six import string_types, text_type
 
 from .geo import GeoCodes
 
+# TODO: remove when Python 2.x is no longer supported
 try:
     cmp
 except NameError: