diff --git a/src/genie_python/genie_waitfor.py b/src/genie_python/genie_waitfor.py
index 76c1bfde..9712d547 100644
--- a/src/genie_python/genie_waitfor.py
+++ b/src/genie_python/genie_waitfor.py
@@ -356,6 +356,10 @@ def start_waiting(
                 )
 
         if block is not None:
+            if not isinstance(block, str):
+                error = "First argument must be a valid block name or None, not {}".format(block)
+                raise TypeError(error)
+
             if not self.api.block_exists(block):
                 raise NameError('No block with the name "{}" exists'.format(block))
             block = self.api.correct_blockname(block, add_prefix=False)
diff --git a/tests/test_genie_waitfor.py b/tests/test_genie_waitfor.py
index 194510c9..9ee1fd62 100644
--- a/tests/test_genie_waitfor.py
+++ b/tests/test_genie_waitfor.py
@@ -28,57 +28,66 @@ def setUp(self):
         self.genie_waitfor = WaitForController(API())
 
     def test_GIVEN_silent_waitfor_time_WHEN_waitfor_time_THEN_no_output(self):
-        capturedOutput = StringIO()
-        sys.stdout = capturedOutput
+        capturedoutput = StringIO()
+        sys.stdout = capturedoutput
         self.genie_waitfor.start_waiting(seconds=0, quiet=True)
         sys.stdout = sys.__stdout__
-        self.assertIs("", capturedOutput.getvalue())
+        self.assertIs("", capturedoutput.getvalue())
 
     def test_GIVEN_waitfor_time_WHEN_waitfor_time_THEN_output(self):
-        capturedOutput = StringIO()
-        sys.stdout = capturedOutput
+        capturedoutput = StringIO()
+        sys.stdout = capturedoutput
         self.genie_waitfor.start_waiting(seconds=0, quiet=False)
         sys.stdout = sys.__stdout__
-        self.assertIsNot("", capturedOutput.getvalue())
+        self.assertIsNot("", capturedoutput.getvalue())
 
     def test_GIVEN_silent_waitfor_uamps_WHEN_waitfor_uamps_THEN_no_output(self):
-        capturedOutput = StringIO()
-        sys.stdout = capturedOutput
+        capturedoutput = StringIO()
+        sys.stdout = capturedoutput
         self.genie_waitfor.start_waiting(uamps=0, quiet=True)
         sys.stdout = sys.__stdout__
-        self.assertIs("", capturedOutput.getvalue())
+        self.assertIs("", capturedoutput.getvalue())
 
     def test_GIVEN_waitfor_uamps_WHEN_waitfor_uamps_THEN_output(self):
-        capturedOutput = StringIO()
-        sys.stdout = capturedOutput
+        capturedoutput = StringIO()
+        sys.stdout = capturedoutput
         self.genie_waitfor.start_waiting(uamps=0, quiet=False)
         sys.stdout = sys.__stdout__
-        self.assertIsNot("", capturedOutput.getvalue())
+        self.assertIsNot("", capturedoutput.getvalue())
 
     def test_GIVEN_silent_waitfor_raw_frames_WHEN_waitfor_raw_frames_THEN_no_output(self):
-        capturedOutput = StringIO()
-        sys.stdout = capturedOutput
+        capturedoutput = StringIO()
+        sys.stdout = capturedoutput
         self.genie_waitfor.start_waiting(raw_frames=0, quiet=True)
         sys.stdout = sys.__stdout__
-        self.assertIs("", capturedOutput.getvalue())
+        self.assertIs("", capturedoutput.getvalue())
 
     def test_GIVEN_waitfor_raw_frames_WHEN_waitfor_raw_frames_THEN_output(self):
-        capturedOutput = StringIO()
-        sys.stdout = capturedOutput
+        capturedoutput = StringIO()
+        sys.stdout = capturedoutput
         self.genie_waitfor.start_waiting(raw_frames=0, quiet=False)
         sys.stdout = sys.__stdout__
-        self.assertIsNot("", capturedOutput.getvalue())
+        self.assertIsNot("", capturedoutput.getvalue())
 
     def test_GIVEN_silent_waitfor_mevents_WHEN_waitfor_mevents_THEN_no_output(self):
-        capturedOutput = StringIO()
-        sys.stdout = capturedOutput
+        capturedoutput = StringIO()
+        sys.stdout = capturedoutput
         self.genie_waitfor.start_waiting(mevents=0, quiet=True)
         sys.stdout = sys.__stdout__
-        self.assertIs("", capturedOutput.getvalue())
+        self.assertIs("", capturedoutput.getvalue())
 
     def test_GIVEN_waitfor_mevents_WHEN_waitfor_mevents_THEN_output(self):
-        capturedOutput = StringIO()
-        sys.stdout = capturedOutput
+        capturedoutput = StringIO()
+        sys.stdout = capturedoutput
         self.genie_waitfor.start_waiting(mevents=0, quiet=False)
         sys.stdout = sys.__stdout__
-        self.assertIsNot("", capturedOutput.getvalue())
+        self.assertIsNot("", capturedoutput.getvalue())
+
+    def test_GIVEN_waitfor_block_WHEN_waitfor_block_integer_THEN_error_output(self):
+        # Exception condition
+        with self.assertRaises(TypeError) as context:
+            self.genie_waitfor.start_waiting(block=10)  # pyright: ignore
+        self.assertEqual(
+            str(context.exception),
+            "First argument must be a valid block name or None, not {}".format(10),
+        )