diff --git a/include/polarssl/pk.h b/include/polarssl/pk.h
index 3806027..00f8cfc 100644
--- a/include/polarssl/pk.h
+++ b/include/polarssl/pk.h
@@ -38,9 +38,13 @@
  */
 typedef enum {
     POLARSSL_PK_NONE=0,
+#if defined(POLARSSL_RSA_C)
     POLARSSL_PK_RSA,
+#endif
+#if defined(POLARSSL_ECP_C)
     POLARSSL_PK_ECKEY,
     POLARSSL_PK_ECKEY_DH,
+#endif
 } pk_type_t;
 
 /**