diff --git a/mopidy/core/library.py b/mopidy/core/library.py
index f2a8b9bd..b8018b16 100644
--- a/mopidy/core/library.py
+++ b/mopidy/core/library.py
@@ -188,20 +188,26 @@ class LibraryController(object):
         if none_set or both_set:
             raise ValueError("One of 'uri' or 'uris' must be set")
 
+        if uri is not None:
+            uris = [uri]
+
         futures = {}
         result = {}
-        backends = self._get_backends_to_uris([uri] if uri else uris)
+        backends = self._get_backends_to_uris(uris)
 
         # TODO: lookup(uris) to backend APIs
         for backend, backend_uris in backends.items():
             for u in backend_uris or []:
                 futures[u] = backend.library.lookup(u)
 
-        for u, future in futures.items():
-            result[u] = future.get()
+        for u in uris:
+            if u in futures:
+                result[u] = futures[u].get()
+            else:
+                result[u] = []
 
         if uri:
-            return result.get(uri, [])
+            return result[uri]
         return result
 
     def refresh(self, uri=None):
diff --git a/tests/core/test_library.py b/tests/core/test_library.py
index b71e5de5..9eacd1a2 100644
--- a/tests/core/test_library.py
+++ b/tests/core/test_library.py
@@ -168,13 +168,20 @@ class CoreLibraryTest(unittest.TestCase):
         result = self.core.library.lookup(uris=['dummy1:a', 'dummy2:a'])
         self.assertEqual(result, {'dummy2:a': [5678], 'dummy1:a': [1234]})
 
-    def test_lookup_returns_nothing_for_dummy3_track(self):
+    def test_lookup_uri_returns_empty_list_for_dummy3_track(self):
         result = self.core.library.lookup('dummy3:a')
 
         self.assertEqual(result, [])
         self.assertFalse(self.library1.lookup.called)
         self.assertFalse(self.library2.lookup.called)
 
+    def test_lookup_uris_returns_empty_list_for_dummy3_track(self):
+        result = self.core.library.lookup(uris=['dummy3:a'])
+
+        self.assertEqual(result, {'dummy3:a': []})
+        self.assertFalse(self.library1.lookup.called)
+        self.assertFalse(self.library2.lookup.called)
+
     def test_refresh_with_uri_selects_dummy1_backend(self):
         self.core.library.refresh('dummy1:a')