diff --git a/include/nuttx/timers/timer.h b/include/nuttx/timers/timer.h
index aedc753f9bd57..b311d96cb7b42 100644
--- a/include/nuttx/timers/timer.h
+++ b/include/nuttx/timers/timer.h
@@ -33,6 +33,7 @@
 #include <signal.h>
 #include <stdbool.h>
 #include <sys/types.h>
+#include <assert.h>
 
 #ifdef CONFIG_TIMER