Add configuration item for the PK module
diff --git a/library/pk_wrap.c b/library/pk_wrap.c
index 9f650b6..7e8a3f1 100644
--- a/library/pk_wrap.c
+++ b/library/pk_wrap.c
@@ -25,6 +25,8 @@
 
 #include "polarssl/config.h"
 
+#if defined(POLARSSL_PK_C)
+
 #include "polarssl/pk_wrap.h"
 
 #if defined(POLARSSL_RSA_C)
@@ -410,3 +412,5 @@
     rsa_alt_free_wrap,
     NULL,
 };
+
+#endif /* POLARSSL_PK_C */