diff --git a/include/polarssl/rsa.h b/include/polarssl/rsa.h
index 8342eec..9078111 100644
--- a/include/polarssl/rsa.h
+++ b/include/polarssl/rsa.h
@@ -27,6 +27,10 @@
 #ifndef POLARSSL_RSA_H
 #define POLARSSL_RSA_H
 
+#include "config.h"
+
+#if defined(POLARSSL_RSA_C)
+
 #include "bignum.h"
 #include "md.h"
 
@@ -520,4 +524,6 @@
 }
 #endif
 
+#endif /* POLARSSL_RSA_C */
+
 #endif /* rsa.h */