diff --git a/fuelclient/cli/error.py b/fuelclient/cli/error.py
index 36bb523..a878242 100644
--- a/fuelclient/cli/error.py
+++ b/fuelclient/cli/error.py
@@ -88,6 +88,10 @@ class ExecutedErrorNonZeroExitCode(FuelClientException):
     """Subshell command returned non-zero exit code."""
 
 
+class LabelEmptyKeyError(BadDataException):
+    """Should be raised when user provides labels with empty key."""
+
+
 def exceptions_decorator(func):
     """Handles HTTP errors and expected exceptions that may occur
     in methods of APIClient class
diff --git a/fuelclient/tests/v1/integration/test_client.py b/fuelclient/tests/v1/integration/test_client.py
index 2fffd6a..e8c9f58 100644
--- a/fuelclient/tests/v1/integration/test_client.py
+++ b/fuelclient/tests/v1/integration/test_client.py
@@ -61,7 +61,7 @@ class TestHandlers(base.BaseTestCase):
         cases = [
             ("env --create --name=TestEnv --release=1 --mode=multinode",
              "400 Client Error: Bad Request (Cannot deploy in multinode "
-             "mode in current release. Need to be one of [u'ha_compact']")
+             "mode in current release. Need to be one of: ha_compact")
         ]
         for cmd, err in cases:
             self.check_for_stderr(cmd, err, check_errors=False)
diff --git a/fuelclient/tests/v2/unit/lib/test_node.py b/fuelclient/tests/v2/unit/lib/test_node.py
index e318057..1b918c5 100644
--- a/fuelclient/tests/v2/unit/lib/test_node.py
+++ b/fuelclient/tests/v2/unit/lib/test_node.py
@@ -156,6 +156,17 @@ class TestNodeFacade(test_api.BaseLibTest):
         self.assertTrue(matcher_put.called)
         self.assertEqual(data, matcher_put.last_request.json())
 
+    def test_set_labels_with_empty_key(self):
+        labels = ['key_1=val_1', ' =   val_2', 'key_3   = ']
+        node_ids = ['42']
+
+        msg = 'Wrong label "{0}" was provided. Label key couldn\'t ' \
+              'be an empty string.'.format(labels[1])
+        with self.assertRaisesRegexp(error.LabelEmptyKeyError, msg):
+            self.client.set_labels_for_nodes(labels=labels, node_ids=node_ids)
+
+        self.assertFalse(self.top_matcher.called)
+
     def test_delete_specific_labels_for_all_nodes(self):
         labels = ['key_1', '   key_3   ']
         data = {'labels': {'key_2': None}}
diff --git a/fuelclient/v1/node.py b/fuelclient/v1/node.py
index bcd3c1c..652a861 100644
--- a/fuelclient/v1/node.py
+++ b/fuelclient/v1/node.py
@@ -112,6 +112,10 @@ class NodeClient(base_v1.BaseV1Client):
 
         for label in labels:
             key, val, _ = self._split_label(label)
+            if not key:
+                msg = 'Wrong label "{0}" was provided. Label key couldn\'t ' \
+                      'be an empty string.'.format(label)
+                raise error.LabelEmptyKeyError(msg)
             labels_to_update[key] = val
 
         if node_ids: