diff --git a/tests/test_validators.py b/tests/test_validators.py
index 4463e9132..6798564f0 100644
--- a/tests/test_validators.py
+++ b/tests/test_validators.py
@@ -202,7 +202,7 @@ def test_operating_system(self):
                 operating_system(s)
 
     def test_task_type(self):
-        for s in ['RUN_COMMAND', 'AUTOMATION', 'LAMBDA', 'STEP_FUNCTION']:
+        for s in ['RUN_COMMAND', 'AUTOMATION', 'LAMBDA', 'STEP_FUNCTIONS']:
             task_type(s)
         for s in ['', 'foo', 'a', 'l@mbda', 'STEPFUNCTION']:
             with self.assertRaises(ValueError):
diff --git a/troposphere/validators.py b/troposphere/validators.py
index b66df138e..3a56b7c2d 100644
--- a/troposphere/validators.py
+++ b/troposphere/validators.py
@@ -266,7 +266,7 @@ def notification_event(events):
 
 
 def task_type(task):
-    valid_tasks = ['RUN_COMMAND', 'AUTOMATION', 'LAMBDA', 'STEP_FUNCTION']
+    valid_tasks = ['RUN_COMMAND', 'AUTOMATION', 'LAMBDA', 'STEP_FUNCTIONS']
     if task not in valid_tasks:
         raise ValueError(
             'TaskType must be one of: "%s"' % (