diff --git a/include/sta/tacos/thread.hpp b/include/sta/tacos/thread.hpp
index 660dd64..902b9b5 100644
--- a/include/sta/tacos/thread.hpp
+++ b/include/sta/tacos/thread.hpp
@@ -39,10 +39,10 @@ namespace sta
 			 * 
 			 * @param name The thread's name. This is used for debugging.
 			 * @param prio The thread's priority. Generally, this should be lower than the manager and statemachine priority.
-			 * @param stack_size The stack size for the task. The default is the stack size specified in the FreeRTOS settings.
-			 * @param cb_size The control block size for the task. The default is the size specified in the FreeRTOS settings.
+			 * @param stack_size The stack size for the task. The default is 0, i.e. the stack size specified in the FreeRTOS settings.
+			 * @param cb_size The control block size for the task. The default is 0, i.e. the size specified in the FreeRTOS settings.
 			 */
-			TacosThread(const char* name, osPriority_t prio, uint32_t stack_size = NULL, uint32_t cb_size = NULL);
+			TacosThread(const char* name, osPriority_t prio, uint32_t stack_size = 0, uint32_t cb_size = 0);
 
 			virtual ~TacosThread();
 
diff --git a/src/thread.cpp b/src/thread.cpp
index 37b6073..a6a2fb4 100644
--- a/src/thread.cpp
+++ b/src/thread.cpp
@@ -19,12 +19,15 @@ namespace sta
 {
 	namespace tacos
 	{
-		TacosThread::TacosThread(const char* name, osPriority_t prio, uint32_t stack_size = NULL, uint32_t cb_size = NULL)
+		TacosThread::TacosThread(const char* name, osPriority_t prio, uint32_t stack_size /* = 0 */, uint32_t cb_size /* = 0 */)
 				: RtosThread(RtosHandle<osThreadId_t>(Handle::Deferred(&instance_))),
 				  instance_{ NULL },
-				  attribs_{ .name = name, .priority = prio, .stack_size=stack_size, .cb_size=cb_size },
+				  attribs_{ .name=name, .cb_size=cb_size, .stack_size=stack_size, .priority=prio },
 				  running_{false}
-		{}
+		{
+			STA_ASSERT(stack_size >= 0);
+			STA_ASSERT(stack_size >= 0);
+		}
 
 		void TacosThread::entry_point(void* arg)
 		{