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
@@ -134,12 +134,11 @@
         """List content missing from storage
 
         Args:
-            contents ([dict]): iterable of dictionaries containing one
-                               key for each checksum algorithm in
-                               :data:`swh.model.hashutil.ALGORITHMS`,
-                               mapped to the corresponding checksum,
-                               and a length key mapped to the content
-                               length.
+            contents ([dict]): iterable of dictionaries whose keys are
+                               either 'length' or an item of
+                               :data:`swh.model.hashutil.ALGORITHMS`;
+                               mapped to the corresponding checksum
+                               (or length).
 
             key_hash (str): name of the column to use as hash id
                             result (default: 'sha1')
@@ -149,8 +148,17 @@
             key_hash column)
         """
         for content in contents:
-            if self._content_key(content) not in self._contents:
-                yield content[key_hash]
+            for (algo, hash_) in content.items():
+                if algo not in DEFAULT_ALGORITHMS:
+                    continue
+                if hash_ not in self._content_indexes.get(algo, []):
+                    yield content[key_hash]
+                    break
+            else:
+                # content_find cannot return None here, because we checked
+                # above that there is a content with matching hashes.
+                if self.content_find(content)['status'] == 'missing':
+                    yield content[key_hash]
 
     def content_missing_per_sha1(self, contents):
         """List content missing from storage based only on sha1.
diff --git a/swh/storage/storage.py b/swh/storage/storage.py
--- a/swh/storage/storage.py
+++ b/swh/storage/storage.py
@@ -305,12 +305,11 @@
         """List content missing from storage
 
         Args:
-            content ([dict]): iterable of dictionaries containing one
-                              key for each checksum algorithm in
-                              :data:`swh.model.hashutil.ALGORITHMS`,
-                              mapped to the corresponding checksum,
-                              and a length key mapped to the content
-                              length.
+            contents ([dict]): iterable of dictionaries whose keys are
+                               either 'length' or an item of
+                               :data:`swh.model.hashutil.ALGORITHMS`;
+                               mapped to the corresponding checksum
+                               (or length).
 
             key_hash (str): name of the column to use as hash id
                             result (default: 'sha1')
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
@@ -11,7 +11,7 @@
 
 import pytest
 
-from hypothesis import given
+from hypothesis import given, strategies
 
 from swh.model import from_disk, identifiers
 from swh.model.hashutil import hash_to_bytes
@@ -609,7 +609,13 @@
              'Content too long')
         )
 
-    def test_content_missing(self):
+    @pytest.mark.property_based
+    @given(strategies.sets(
+        elements=strategies.sampled_from(
+            ['sha256', 'sha1_git', 'blake2s256']),
+        min_size=1))
+    def test_content_missing(self, algos):
+        algos |= {'sha1'}
         cont2 = self.cont2
         missing_cont = self.missing_cont
         self.storage.content_add([cont2])
@@ -617,7 +623,7 @@
         missing_per_hash = defaultdict(list)
         for i in range(256):
             test_content = missing_cont.copy()
-            for hash in ['sha1', 'sha256', 'sha1_git', 'blake2s256']:
+            for hash in algos:
                 test_content[hash] = bytes([i]) + test_content[hash][1:]
                 missing_per_hash[hash].append(test_content[hash])
             test_contents.append(test_content)
@@ -627,7 +633,7 @@
             missing_per_hash['sha1']
         )
 
-        for hash in ['sha1', 'sha256', 'sha1_git', 'blake2s256']:
+        for hash in algos:
             self.assertCountEqual(
                 self.storage.content_missing(test_contents, key_hash=hash),
                 missing_per_hash[hash]