diff --git a/src/timer.cpp b/src/timer.cpp
index 6302ecd..7e42d1c 100644
--- a/src/timer.cpp
+++ b/src/timer.cpp
@@ -1,5 +1,6 @@
 #include <sta/rtos/timer.hpp>
 #include <sta/debug/debug.hpp>
+#include <sta/debug/assert.hpp>
 
 namespace sta {
 	RtosTimer::RtosTimer(){}
@@ -10,7 +11,7 @@ namespace sta {
         timer_attr_.cb_size = sizeof(osTimerAttr_t);
 
         timer_id_ = osTimerNew(callback, osTimerOnce, arg, &timer_attr_);
-        STA_ASSERT_MSG(timer_id != 0, "Failed to initialize timer");
+        STA_ASSERT_MSG(timer_id_ != 0, "Failed to initialize timer");
     }
 
     RtosTimer::~RtosTimer() {