diff --git a/python/ray/tune/config_parser.py b/python/ray/tune/config_parser.py
index 484b47362..05552c3b1 100644
--- a/python/ray/tune/config_parser.py
+++ b/python/ray/tune/config_parser.py
@@ -19,7 +19,7 @@ def json_to_resources(data):
                 "Unknown resource type {}, must be one of {}".format(
                     k, Resources._fields))
     return Resources(
-        data.get("cpu", 0), data.get("gpu", 0),
+        data.get("cpu", 1), data.get("gpu", 0),
         data.get("driver_cpu_limit"), data.get("driver_gpu_limit"))
 
 
diff --git a/python/ray/tune/trial_runner.py b/python/ray/tune/trial_runner.py
index c8f5ad912..557ce8a64 100644
--- a/python/ray/tune/trial_runner.py
+++ b/python/ray/tune/trial_runner.py
@@ -129,7 +129,6 @@ class TrialRunner(object):
 
         cpu_avail = self._avail_resources.cpu - self._committed_resources.cpu
         gpu_avail = self._avail_resources.gpu - self._committed_resources.gpu
-        assert cpu_avail >= 0 and gpu_avail >= 0
         return resources.cpu <= cpu_avail and resources.gpu <= gpu_avail
 
     def _can_launch_more(self):