diff --git a/python/ray/tune/trial_runner.py b/python/ray/tune/trial_runner.py
index 2fc77c9b3..ef6330deb 100644
--- a/python/ray/tune/trial_runner.py
+++ b/python/ray/tune/trial_runner.py
@@ -156,7 +156,7 @@ class TrialRunner(object):
                 # have been lost
 
     def _process_events(self):
-        [result_id], _ = ray.wait(self._running.keys())
+        [result_id], _ = ray.wait(list(self._running.keys()))
         trial = self._running[result_id]
         del self._running[result_id]
         try:
diff --git a/python/ray/worker.py b/python/ray/worker.py
index dff99df55..a1255bd3e 100644
--- a/python/ray/worker.py
+++ b/python/ray/worker.py
@@ -2223,6 +2223,22 @@ def wait(object_ids, num_returns=1, timeout=None, worker=global_worker):
         A list of object IDs that are ready and a list of the remaining object
             IDs.
     """
+
+    if isinstance(object_ids, ray.local_scheduler.ObjectID):
+        raise TypeError(
+            "wait() expected a list of ObjectID, got a single ObjectID")
+
+    if not isinstance(object_ids, list):
+        raise TypeError("wait() expected a list of ObjectID, got {}".format(
+            type(object_ids)))
+
+    if worker.mode != PYTHON_MODE:
+        for object_id in object_ids:
+            if not isinstance(object_id, ray.local_scheduler.ObjectID):
+                raise TypeError(
+                    "wait() expected a list of ObjectID, "
+                    "got list containing {}".format(type(object_id)))
+
     check_connected(worker)
     with log_span("ray:wait", worker=worker):
         check_main_thread()
diff --git a/test/runtest.py b/test/runtest.py
index 5f4505781..b1b3c4e63 100644
--- a/test/runtest.py
+++ b/test/runtest.py
@@ -749,6 +749,15 @@ class APITest(unittest.TestCase):
         self.assertEqual(ready_ids, [])
         self.assertEqual(remaining_ids, [])
 
+        # Verify that incorrect usage raises a TypeError.
+        x = ray.put(1)
+        with self.assertRaises(TypeError):
+            ray.wait(x)
+        with self.assertRaises(TypeError):
+            ray.wait(1)
+        with self.assertRaises(TypeError):
+            ray.wait([1])
+
     def testMultipleWaitsAndGets(self):
         # It is important to use three workers here, so that the three tasks
         # launched in this experiment can run at the same time.