diff --git a/programs/pkey/rsa_encrypt.c b/programs/pkey/rsa_encrypt.c
index 58817e3..2f88209 100644
--- a/programs/pkey/rsa_encrypt.c
+++ b/programs/pkey/rsa_encrypt.c
@@ -29,17 +29,22 @@
 #if defined(POLARSSL_PLATFORM_C)
 #include "polarssl/platform.h"
 #else
-#define polarssl_printf     printf
+#include <stdio.h>
 #define polarssl_fprintf    fprintf
+#define polarssl_printf     printf
 #endif
 
-#include <string.h>
-#include <stdio.h>
-
+#if defined(POLARSSL_BIGNUM_C) && defined(POLARSSL_RSA_C) &&\
+    defined(POLARSSL_ENTROPY_C) && defined(POLARSSL_FS_IO) &&\
+    defined(POLARSSL_CTR_DRBG_C)
 #include "polarssl/rsa.h"
 #include "polarssl/entropy.h"
 #include "polarssl/ctr_drbg.h"
 
+#include <stdio.h>
+#include <string.h>
+#endif
+
 #if !defined(POLARSSL_BIGNUM_C) || !defined(POLARSSL_RSA_C) ||  \
     !defined(POLARSSL_ENTROPY_C) || !defined(POLARSSL_FS_IO) || \
     !defined(POLARSSL_CTR_DRBG_C)