diff --git a/hooks/config-changed b/hooks/config-changed
index bfdac9a..7a9db07 100755
--- a/hooks/config-changed
+++ b/hooks/config-changed
@@ -256,7 +256,7 @@ targets = {os.path.join(target_prefix, 'binlog.cnf'): binlog_cnf,
            }
 
 need_restart = False
-for target,content in targets.iteritems():
+for target,content in targets.items():
     tdir = os.path.dirname(target)
     if len(content) == 0 and os.path.exists(target):
         os.unlink(target)
diff --git a/hooks/shared_db_relations.py b/hooks/shared_db_relations.py
index 3c34b13..615fd55 100755
--- a/hooks/shared_db_relations.py
+++ b/hooks/shared_db_relations.py
@@ -9,6 +9,7 @@
 
 import subprocess
 import json
+from collections import defaultdict
 import lib.utils as utils
 import lib.cluster_utils as cluster
 
@@ -33,8 +34,7 @@ def relation_get():
 
 def unit_sorted(units):
     """Return a sorted list of unit names."""
-    return sorted(
-        units, lambda a, b: cmp(int(a.split('/')[-1]), int(b.split('/')[-1])))
+    return sorted(units, lambda name: int(name.split('/')[-1]))
 
 
 def get_unit_addr(relid, unitid):
@@ -109,12 +109,9 @@ def shared_db_changed():
         #    }
         # }
         #
-        databases = {}
-        for k, v in settings.iteritems():
-            db = k.split('_')[0]
-            x = '_'.join(k.split('_')[1:])
-            if db not in databases:
-                databases[db] = {}
+        databases = defaultdict(dict)
+        for k, v in settings.items():
+            db, x = k.split('_', 1)
             databases[db][x] = v
 
         return_data = {}
diff --git a/scripts/charm_helpers_sync.py b/scripts/charm_helpers_sync.py
index 3249f1e..ebfb5f1 100755
--- a/scripts/charm_helpers_sync.py
+++ b/scripts/charm_helpers_sync.py
@@ -159,7 +159,7 @@ def sync_helpers(include, src, dest, options=None):
             sync(src, dest, inc, opts)
         elif isinstance(inc, dict):
             # could also do nested dicts here.
-            for k, v in inc.iteritems():
+            for k, v in inc.items():
                 if isinstance(v, list):
                     for m in v:
                         inc, opts = extract_options(m, global_options)