diff --git a/library/pk_wrap.c b/library/pk_wrap.c
index d6dea12..994320f 100644
--- a/library/pk_wrap.c
+++ b/library/pk_wrap.c
@@ -50,10 +50,12 @@
 #define polarssl_free       free
 #endif
 
+#if defined(POLARSSL_PK_RSA_ALT_SUPPORT)
 /* Implementation that should never be optimized out by the compiler */
 static void polarssl_zeroize( void *v, size_t n ) {
     volatile unsigned char *p = v; while( n-- ) *p++ = 0;
 }
+#endif
 
 #if defined(POLARSSL_RSA_C)
 static int rsa_can_do( pk_type_t type )
@@ -377,6 +379,7 @@
 };
 #endif /* POLARSSL_ECDSA_C */
 
+#if defined(POLARSSL_PK_RSA_ALT_SUPPORT)
 /*
  * Support for alternative RSA-private implementations
  */
@@ -488,4 +491,6 @@
     NULL,
 };
 
+#endif /* POLARSSL_PK_RSA_ALT_SUPPORT */
+
 #endif /* POLARSSL_PK_C */