diff --git a/ChangeLog b/ChangeLog
index 5e0493a..342be8e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2017-10-03  NIIBE Yutaka  <gniibe@fsij.org>
 
+	* polarssl/library/rsa.c: Don't include stdlib.h.
+	* src/gnuk-malloc.h: Rename from stdlib.h.
+	* polarssl/library/bignum.c: Include gnuk-malloc.h.
+
 	* src/Makefile (build/flash.data): Generate.
 
 	* src/main.c (flash_addr_key_storage_start)
diff --git a/polarssl/library/bignum.c b/polarssl/library/bignum.c
index 108090d..4a9a9d8 100644
--- a/polarssl/library/bignum.c
+++ b/polarssl/library/bignum.c
@@ -37,7 +37,7 @@
 #include "polarssl/bignum.h"
 #include "polarssl/bn_mul.h"
 
-#include <stdlib.h>
+#include <gnuk-malloc.h>
 
 #define ciL    (sizeof(t_uint))         /* chars in limb  */
 #define biL    (ciL << 3)               /* bits  in limb  */
diff --git a/polarssl/library/rsa.c b/polarssl/library/rsa.c
index 4885e9e..3e9b829 100644
--- a/polarssl/library/rsa.c
+++ b/polarssl/library/rsa.c
@@ -39,7 +39,6 @@
 #include "polarssl/md.h"
 #endif
 
-#include <stdlib.h>
 #include <stdio.h>
 
 /*
diff --git a/src/gnuk-malloc.h b/src/gnuk-malloc.h
new file mode 100644
index 0000000..e9c55d2
--- /dev/null
+++ b/src/gnuk-malloc.h
@@ -0,0 +1,16 @@
+/*
+ * Gnuk uses its own malloc functions.
+ *
+ * The intention is no-dependency to C library.  But, we provide
+ * malloc and free here, since RSA routines uses malloc/free
+ * internally.
+ *
+ */
+
+#include <stddef.h> /* NULL and size_t */
+
+#define malloc(size)	gnuk_malloc (size)
+#define free(p)		gnuk_free (p)
+
+void *gnuk_malloc (size_t);
+void gnuk_free (void *);
diff --git a/src/stdlib.h b/src/stdlib.h
deleted file mode 100644
index bc2d05b..0000000
--- a/src/stdlib.h
+++ /dev/null
@@ -1,22 +0,0 @@
-/*
- * stdlib.h replacement to replace malloc functions
- *
- * The intention is that no dependency to C library.  But since RSA
- * routines uses malloc/free, we provide malloc and free.
- *
- * For GNU/Linux emulation, we can use C library.
- */
-
-#include <stddef.h> /* NULL and size_t */
-
-#define malloc(size)	gnuk_malloc (size)
-#define free(p)		gnuk_free (p)
-
-void *gnuk_malloc (size_t);
-void gnuk_free (void *);
-
-#ifdef GNU_LINUX_EMULATION
-long int random(void);
-void srandom(unsigned int seed);
-void exit(int status);
-#endif