diff --git a/include/tlibc/std.h b/include/tlibc/std.h
index f07e4e6..d0c049f 100755
--- a/include/tlibc/std.h
+++ b/include/tlibc/std.h
@@ -1,6 +1,6 @@
 #pragma once
 
-#if __cplusplus
+#ifdef __cplusplus
 extern "C" {
 #endif
 
@@ -142,6 +142,6 @@ typedef void (*Destructor_t)(void* self);
     CODE; \
     PRAGMA_WARNING_POP
 
-#if __cplusplus
+#ifdef __cplusplus
 }
 #endif
\ No newline at end of file
diff --git a/include/tlibc/time.h b/include/tlibc/time.h
index ec6e4d3..4d1d10f 100644
--- a/include/tlibc/time.h
+++ b/include/tlibc/time.h
@@ -1,6 +1,6 @@
 #pragma once
 
-#if __cplusplus
+#ifdef __cplusplus
 extern "C" {
 #endif
 
@@ -70,6 +70,6 @@ USAGE:
 #define DT_expand(dt) dt.d.year, dt.d.month, dt.d.month_day, dt.t.hour, dt.t.min, dt.t.sec
 #define DT_expand_subsec(dt) dt.d.year, dt.d.month, dt.d.month_day, dt.t.hour, dt.t.min, dt.t.sec, dt.t.nsec
 
-#if __cplusplus
+#ifdef __cplusplus
 }
 #endif