diff --git a/include/polarssl/bignum.h b/include/polarssl/bignum.h
index 1807439..7c3961e 100644
--- a/include/polarssl/bignum.h
+++ b/include/polarssl/bignum.h
@@ -24,7 +24,6 @@
 #ifndef POLARSSL_BIGNUM_H
 #define POLARSSL_BIGNUM_H
 
-#include <stdio.h>
 #include <string.h>
 
 #if !defined(POLARSSL_CONFIG_FILE)
@@ -33,6 +32,10 @@
 #include POLARSSL_CONFIG_FILE
 #endif
 
+#if defined(POLARSSL_FS_IO)
+#include <stdio.h>
+#endif
+
 #if defined(_MSC_VER) && !defined(EFIX64) && !defined(EFI32)
 #include <basetsd.h>
 #if (_MSC_VER <= 1200)