diff --git a/components/libc/compilers/common/ctime.c b/components/libc/compilers/common/ctime.c
index b6d6135..80f1c27 100644
--- a/components/libc/compilers/common/ctime.c
+++ b/components/libc/compilers/common/ctime.c
@@ -40,6 +40,8 @@
 #define DBG_LVL    DBG_INFO
 #include <rtdbg.h>
 
+#undef __isleap
+
 #define _WARNING_NO_RTC "Cannot find a RTC device!"
 
 /* seconds per day */