diff --git a/src/calls-contacts-provider.c b/src/calls-contacts-provider.c
index 5652359..4640a60 100644
--- a/src/calls-contacts-provider.c
+++ b/src/calls-contacts-provider.c
@@ -422,9 +422,9 @@ calls_contacts_provider_lookup_id (CallsContactsProvider *self,
   g_return_val_if_fail (CALLS_IS_CONTACTS_PROVIDER (self), NULL);
 
   if (STR_IS_NULL_OR_EMPTY (id))
-    return NULL;
-
-  best_match = g_hash_table_lookup (self->best_matches, id);
+    best_match = g_hash_table_lookup (self->best_matches, "");
+  else
+    best_match = g_hash_table_lookup (self->best_matches, id);
 
   if (best_match)
     return g_object_ref (best_match);
@@ -435,7 +435,7 @@ calls_contacts_provider_lookup_id (CallsContactsProvider *self,
                           best_match, "country-code",
                           G_BINDING_SYNC_CREATE);
 
-  g_hash_table_insert (self->best_matches, g_strdup (id), best_match);
+  g_hash_table_insert (self->best_matches, g_strdup (id ?: ""), best_match);
 
   return g_object_ref (best_match);
 }
diff --git a/tests/test-contacts.c b/tests/test-contacts.c
index b974d2c..c970b34 100644
--- a/tests/test-contacts.c
+++ b/tests/test-contacts.c
@@ -16,10 +16,10 @@ test_contacts_null_contact (void)
 {
   g_autoptr (CallsContactsProvider) contacts_provider =
     calls_contacts_provider_new ();
-  CallsBestMatch *best_match;
+  g_autoptr (CallsBestMatch) best_match = NULL;
 
   best_match = calls_contacts_provider_lookup_id (contacts_provider, NULL);
-  g_assert_null (best_match);
+  g_assert_nonnull (best_match);
 
   g_assert_cmpstr (calls_best_match_get_primary_info (best_match), ==, "Anonymous caller");
   g_assert_cmpstr (calls_best_match_get_secondary_info (best_match), ==, "");