diff --git a/programs/hash/sha2sum.c b/programs/hash/sha2sum.c
index 3fc1baa..a9c5698 100644
--- a/programs/hash/sha2sum.c
+++ b/programs/hash/sha2sum.c
@@ -29,15 +29,18 @@
 #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_SHA256_C) && defined(POLARSSL_FS_IO)
 #include "polarssl/sha256.h"
 
+#include <stdio.h>
+#include <string.h>
+#endif
+
 #if !defined(POLARSSL_SHA256_C) || !defined(POLARSSL_FS_IO)
 int main( int argc, char *argv[] )
 {