diff --git a/swh/storage/in_memory.py b/swh/storage/in_memory.py
--- a/swh/storage/in_memory.py
+++ b/swh/storage/in_memory.py
@@ -263,7 +263,9 @@
             )
         yield from self.objstorage.content_get(contents)
 
-    def content_get_range(self, start, end, limit=1000):
+    def content_get_range(
+        self, start: bytes, end: bytes, limit: int = 1000
+    ) -> Dict[str, Any]:
         if limit is None:
             raise StorageArgumentException("limit should not be None")
         sha1s = (
@@ -271,7 +273,7 @@
             for sha1 in self._sorted_sha1s.iter_from(start)
             for content_key in self._content_indexes["sha1"][sha1]
         )
-        matched = []
+        matched: List[Dict[str, Any]] = []
         next_content = None
         for sha1, key in sha1s:
             if sha1 > end:
diff --git a/swh/storage/interface.py b/swh/storage/interface.py
--- a/swh/storage/interface.py
+++ b/swh/storage/interface.py
@@ -177,7 +177,9 @@
 
     @deprecated
     @remote_api_endpoint("content/range")
-    def content_get_range(self, start, end, limit=1000):
+    def content_get_range(
+        self, start: bytes, end: bytes, limit: int = 1000
+    ) -> Dict[str, Any]:
         """Retrieve contents within range [start, end] bound by limit.
 
         Note that this function may return more than one blob per hash. The
@@ -185,11 +187,11 @@
         will count twice toward the limit).
 
         Args:
-            **start** (bytes): Starting identifier range (expected smaller
+            **start**: Starting identifier range (expected smaller
                            than end)
-            **end** (bytes): Ending identifier range (expected larger
+            **end**: Ending identifier range (expected larger
                              than start)
-            **limit** (int): Limit result (default to 1000)
+            **limit**: Limit result (default to 1000)
 
         Returns:
             a dict with keys:
diff --git a/swh/storage/storage.py b/swh/storage/storage.py
--- a/swh/storage/storage.py
+++ b/swh/storage/storage.py
@@ -278,7 +278,9 @@
 
     @timed
     @db_transaction()
-    def content_get_range(self, start, end, limit=1000, db=None, cur=None):
+    def content_get_range(
+        self, start: bytes, end: bytes, limit: int = 1000, db=None, cur=None
+    ) -> Dict[str, Any]:
         if limit is None:
             raise StorageArgumentException("limit should not be None")
         contents = []