diff --git a/library/pk.c b/library/pk.c
index d1bd215..a1c7c1d 100644
--- a/library/pk.c
+++ b/library/pk.c
@@ -108,6 +108,7 @@
     return( 0 );
 }
 
+#if defined(POLARSSL_RSA_C)
 /*
  * Set RSA padding
  */
@@ -121,6 +122,7 @@
 
     return( 0 );
 }
+#endif /* POLARSSL_RSA_C */
 
 /*
  * Initialize an RSA-alt context