diff --git a/abstract-machine/klib/include/klib.h b/abstract-machine/klib/include/klib.h
index ecb24c8..33e1a78 100644
--- a/abstract-machine/klib/include/klib.h
+++ b/abstract-machine/klib/include/klib.h
@@ -9,7 +9,7 @@
 extern "C" {
 #endif
 
-//#define __NATIVE_USE_KLIB__
+// #define __NATIVE_USE_KLIB__
 
 // string.h
 void  *memset    (void *s, int c, size_t n);
diff --git a/abstract-machine/klib/src/printf.c b/abstract-machine/klib/src/printf.c
index d79f9d9..a4969b4 100644
--- a/abstract-machine/klib/src/printf.c
+++ b/abstract-machine/klib/src/printf.c
@@ -29,16 +29,15 @@ int num_to_ascii(int num, int power, int size, char *buf) {
     return ret;
 }
 
-static inline int print_fmt(char **out, int n, const char** fmt, void* _ap) {
-    va_list ap = *(va_list*)_ap;
+static inline int print_fmt(char **out, int n, const char** fmt, va_list (*ap)) {
     int ret = 0;
     switch (**fmt) {
         case 'd':
-            ret = num_to_ascii(va_arg(ap, int), 10, n, *out);
+            ret = num_to_ascii(va_arg(*ap, int), 10, n, *out);
             (*out) += ret;
             break;
         case 's':
-            const char* str = va_arg(ap, const char*);
+            const char* str = va_arg(*ap, const char*);
             if (ret > n) break;
             for (; *str; str ++, (*out) ++, ret ++ ) {
                 if (ret >= n) {
@@ -48,20 +47,19 @@ static inline int print_fmt(char **out, int n, const char** fmt, void* _ap) {
             }
             break;
         case 'c':
-            char ch = va_arg(ap, int);
+            char ch = va_arg(*ap, int);
             ret = 1;
             **out = ch;
             (*out) ++;
             break;
         case 'x':
-            ret = num_to_ascii(va_arg(ap, int), 16, n, *out);
+            ret = num_to_ascii(va_arg(*ap, int), 16, n, *out);
             (*out) += ret;
             break;
         default:
             break;
     }
     (*fmt) ++;
-    *(va_list*)_ap = ap;
     return ret;
 }
 
@@ -71,7 +69,7 @@ int rvsnprintf(char* out, size_t n, const char* fmt, va_list ap) {
         if (*fmt == '%') {
             // FIXME
             fmt++;
-            print_fmt(&out, 123, &fmt, &ap);
+            print_fmt(&out, 123, &fmt, (va_list*)&ap);
             continue;
         }
         *out = *fmt;
diff --git a/abstract-machine/klib/src/stdlib.c b/abstract-machine/klib/src/stdlib.c
index e421ca7..13c4e25 100644
--- a/abstract-machine/klib/src/stdlib.c
+++ b/abstract-machine/klib/src/stdlib.c
@@ -40,7 +40,7 @@ void *malloc(size_t size) {
   ptr += size;
   return ptr - size;
 #endif
-  return NULL;
+  return ptr;
 }
 
 void free(void *ptr) {