diff --git a/tensorflowonspark/TFNode.py b/tensorflowonspark/TFNode.py
index b4b5f5d..0a36cd3 100644
--- a/tensorflowonspark/TFNode.py
+++ b/tensorflowonspark/TFNode.py
@@ -23,7 +23,10 @@
 from . import compat, marker
 
 logger = logging.getLogger(__name__)
-TF_VERSION = pkg_resources.get_distribution('tensorflow').version
+try:
+  TF_VERSION = pkg_resources.get_distribution('tensorflow').version
+except pkg_resources.DistributionNotFound:
+  TF_VERSION = pkg_resources.get_distribution('tensorflow-cpu').version
 
 
 def hdfs_path(ctx, path):
diff --git a/tensorflowonspark/TFParallel.py b/tensorflowonspark/TFParallel.py
index aef7c88..bb37d99 100644
--- a/tensorflowonspark/TFParallel.py
+++ b/tensorflowonspark/TFParallel.py
@@ -47,7 +47,7 @@ def _run(it):
       nodes = [t.address for t in tasks]
       num_workers = len(nodes)
     else:
-      nodes = None
+      nodes = []
       num_workers = num_executors
 
     # use the placement info to help allocate GPUs
diff --git a/tensorflowonspark/TFSparkNode.py b/tensorflowonspark/TFSparkNode.py
index 995a0f5..54a05cd 100644
--- a/tensorflowonspark/TFSparkNode.py
+++ b/tensorflowonspark/TFSparkNode.py
@@ -31,7 +31,10 @@
 from . import util
 
 logger = logging.getLogger(__name__)
-TF_VERSION = pkg_resources.get_distribution('tensorflow').version
+try:
+  TF_VERSION = pkg_resources.get_distribution('tensorflow').version
+except pkg_resources.DistributionNotFound:
+  TF_VERSION = pkg_resources.get_distribution('tensorflow-cpu').version
 
 
 def _has_spark_resource_api():
@@ -502,7 +505,7 @@ def _train(iter):
       joinThr = Thread(target=queue.join)
       joinThr.start()
       timeout = feed_timeout
-      while (joinThr.isAlive()):
+      while (joinThr.is_alive()):
         if (not equeue.empty()):
           e_str = equeue.get()
           raise Exception("Exception in worker:\n" + e_str)
@@ -570,7 +573,7 @@ def _inference(iter):
     joinThr = Thread(target=queue_in.join)
     joinThr.start()
     timeout = feed_timeout
-    while (joinThr.isAlive()):
+    while (joinThr.is_alive()):
       if (not equeue.empty()):
         e_str = equeue.get()
         raise Exception("Exception in worker:\n" + e_str)
diff --git a/tensorflowonspark/pipeline.py b/tensorflowonspark/pipeline.py
index 159bdda..b3da0ef 100755
--- a/tensorflowonspark/pipeline.py
+++ b/tensorflowonspark/pipeline.py
@@ -31,7 +31,10 @@
 
 
 logger = logging.getLogger(__name__)
-TF_VERSION = pkg_resources.get_distribution('tensorflow').version
+try:
+  TF_VERSION = pkg_resources.get_distribution('tensorflow').version
+except pkg_resources.DistributionNotFound:
+  TF_VERSION = pkg_resources.get_distribution('tensorflow-cpu').version
 
 
 # TensorFlowOnSpark Params
diff --git a/tensorflowonspark/util.py b/tensorflowonspark/util.py
index fb4cc73..875ffa4 100644
--- a/tensorflowonspark/util.py
+++ b/tensorflowonspark/util.py
@@ -30,7 +30,7 @@ def single_node_env(num_gpus=1, worker_index=-1, nodes=[]):
 
   if gpu_info.is_gpu_available() and num_gpus > 0:
     # reserve GPU(s), if requested
-    if worker_index >= 0 and len(nodes) > 0:
+    if worker_index >= 0 and nodes and len(nodes) > 0:
       # compute my index relative to other nodes on the same host, if known
       my_addr = nodes[worker_index]
       my_host = my_addr.split(':')[0]
diff --git a/tests/test_TFSparkNode.py b/tests/test_TFSparkNode.py
index 12ce8f4..cd823c4 100644
--- a/tests/test_TFSparkNode.py
+++ b/tests/test_TFSparkNode.py
@@ -46,8 +46,10 @@ def fn(args, ctx):
     map_fn = TFSparkNode.run(fn, tf_args, self.cluster_meta, self.tensorboard, self.log_dir, self.queues, self.background)
     map_fn([0])
 
-  def test_gpu_unavailable(self):
+  @patch('tensorflowonspark.gpu_info.is_gpu_available')
+  def test_gpu_unavailable(self, mock_available):
     """Request GPU with no GPUs available, expecting an exception"""
+    mock_available.return_value = False
     self.parser.add_argument("--num_gpus", help="number of gpus to use", type=int)
     tf_args = self.parser.parse_args(["--num_gpus", "1"])