diff --git a/swh/storage/api/client.py b/swh/storage/api/client.py
--- a/swh/storage/api/client.py
+++ b/swh/storage/api/client.py
@@ -108,7 +108,7 @@
         })
 
     def snapshot_get_branches(self, snapshot_id, branches_from=b'',
-                              branches_count=None, target_types=None):
+                              branches_count=1000, target_types=None):
         return self.post('snapshot/get_branches', {
             'snapshot_id': snapshot_id,
             'branches_from': branches_from,
diff --git a/swh/storage/storage.py b/swh/storage/storage.py
--- a/swh/storage/storage.py
+++ b/swh/storage/storage.py
@@ -20,13 +20,16 @@
 from .exc import StorageDBError
 from .algos import diff
 
-from swh.model.hashutil import ALGORITHMS
+from swh.model.hashutil import ALGORITHMS, hash_to_bytes
 from swh.objstorage import get_objstorage
 from swh.objstorage.exc import ObjNotFoundError
 
 # Max block size of contents to return
 BULK_BLOCK_CONTENT_LEN_MAX = 10000
 
+EMPTY_SNAPSHOT_ID = hash_to_bytes('1a8893e6a86f444e8be8e7bda6cb34fb1735a00e')
+"""Identifier for the empty snapshot"""
+
 
 class Storage():
     """SWH storage proxy, encompassing DB and object storage
@@ -745,39 +748,8 @@
                   or :const:`None` if the snapshot has less than 1000
                   branches.
         """
-        max_branches = 1000
-        branches = {}
-        next_branch = None
-        fetched_branches = list(db.snapshot_get_by_id(
-            snapshot_id, branches_count=max_branches+1, cur=cur))
-        for branch in fetched_branches[:max_branches]:
-            branch = dict(zip(db.snapshot_get_cols, branch))
-            del branch['snapshot_id']
-            name = branch.pop('name')
-            if branch == {'target': None, 'target_type': None}:
-                branch = None
-            branches[name] = branch
-
-        if len(fetched_branches) > max_branches:
-            branch = dict(zip(db.snapshot_get_cols, fetched_branches[-1]))
-            next_branch = branch['name']
 
-        if branches:
-            return {
-                'id': snapshot_id,
-                'branches': branches,
-                'next_branch': next_branch
-            }
-
-        if db.snapshot_exists(snapshot_id, cur):
-            # empty snapshot
-            return {
-                'id': snapshot_id,
-                'branches': {},
-                'next_branch': None
-            }
-
-        return None
+        return self.snapshot_get_branches(snapshot_id, db=db, cur=cur)
 
     @db_transaction(statement_timeout=2000)
     def snapshot_get_by_origin_visit(self, origin, visit, db=None, cur=None):
@@ -863,7 +835,7 @@
 
     @db_transaction(statement_timeout=2000)
     def snapshot_get_branches(self, snapshot_id, branches_from=b'',
-                              branches_count=None, target_types=None,
+                              branches_count=1000, target_types=None,
                               db=None, cur=None):
         """Get the content, possibly partial, of a snapshot with the given id
 
@@ -881,14 +853,30 @@
                 contained in that list are `'content', 'directory',
                 'revision', 'release', 'snapshot', 'alias'`)
         Returns:
-            dict: a dict with two keys:
+            dict: a dict with three keys:
                 * **id**: identifier of the snapshot
                 * **branches**: a dict of branches contained in the snapshot
                   whose keys are the branches' names.
+                * **next_branch**: the name of the first branch not returned
+                  or :const:`None` if the snapshot has less than
+                  `branches_count` branches after `branches_from` included.
         """
+        if snapshot_id == EMPTY_SNAPSHOT_ID:
+            return {
+                'id': snapshot_id,
+                'branches': {},
+                'next_branch': None,
+            }
+
         branches = {}
-        for branch in db.snapshot_get_by_id(snapshot_id, branches_from,
-                                            branches_count, target_types, cur):
+        next_branch = None
+
+        fetched_branches = list(db.snapshot_get_by_id(
+            snapshot_id, branches_from=branches_from,
+            branches_count=branches_count+1, target_types=target_types,
+            cur=cur,
+        ))
+        for branch in fetched_branches[:branches_count]:
             branch = dict(zip(db.snapshot_get_cols, branch))
             del branch['snapshot_id']
             name = branch.pop('name')
@@ -896,11 +884,16 @@
                 branch = None
             branches[name] = branch
 
-        if branches:
-            return {'id': snapshot_id, 'branches': branches}
+        if len(fetched_branches) > branches_count:
+            branch = dict(zip(db.snapshot_get_cols, fetched_branches[-1]))
+            next_branch = branch['name']
 
-        if db.snapshot_exists(snapshot_id, cur):
-            return {'id': snapshot_id, 'branches': {}}
+        if branches:
+            return {
+                'id': snapshot_id,
+                'branches': branches,
+                'next_branch': next_branch,
+            }
 
         return None
 
diff --git a/swh/storage/tests/test_storage.py b/swh/storage/tests/test_storage.py
--- a/swh/storage/tests/test_storage.py
+++ b/swh/storage/tests/test_storage.py
@@ -1228,6 +1228,7 @@
                 name: branches[name]
                 for name in branch_names[rel_idx:]
             },
+            'next_branch': None,
         }
 
         self.assertEqual(snapshot, expected_snapshot)
@@ -1240,6 +1241,7 @@
             'branches': {
                  branch_names[0]: branches[branch_names[0]],
             },
+            'next_branch': b'content',
         }
         self.assertEqual(snapshot, expected_snapshot)
 
@@ -1253,6 +1255,7 @@
                 name: branches[name]
                 for name in branch_names[dir_idx:dir_idx + 3]
             },
+            'next_branch': branch_names[dir_idx + 3],
         }
 
         self.assertEqual(snapshot, expected_snapshot)
@@ -1278,6 +1281,7 @@
                 for name, tgt in branches.items()
                 if tgt and tgt['target_type'] in ['release', 'revision']
             },
+            'next_branch': None,
         }
 
         self.assertEqual(snapshot, expected_snapshot)
@@ -1292,6 +1296,7 @@
                 for name, tgt in branches.items()
                 if tgt and tgt['target_type'] == 'alias'
             },
+            'next_branch': None,
         }
 
         self.assertEqual(snapshot, expected_snapshot)