diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index b13790d..52cec1d 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -769,6 +769,15 @@
 //#define POLARSSL_MEMORY_BACKTRACE
 
 /**
+ * \def POLARSSL_PK_RSA_ALT_SUPPORT
+ *
+ * Support external private RSA keys (eg from a HSM) in the PK layer.
+ *
+ * Comment this macro to disable support for external private RSA keys.
+ */
+#define POLARSSL_PK_RSA_ALT_SUPPORT
+
+/**
  * \def POLARSSL_PKCS1_V15
  *
  * Enable support for PKCS#1 v1.5 encoding.
diff --git a/include/mbedtls/pk.h b/include/mbedtls/pk.h
index 8fda581..207d354 100644
--- a/include/mbedtls/pk.h
+++ b/include/mbedtls/pk.h
@@ -197,6 +197,7 @@
     void *              pk_ctx;     /**< Underlying public key context  */
 } pk_context;
 
+#if defined(POLARSSL_PK_RSA_ALT_SUPPORT)
 /**
  * \brief           Types for RSA-alt abstraction
  */
@@ -208,6 +209,7 @@
                     int mode, md_type_t md_alg, unsigned int hashlen,
                     const unsigned char *hash, unsigned char *sig );
 typedef size_t (*pk_rsa_alt_key_len_func)( void *ctx );
+#endif /* POLARSSL_PK_RSA_ALT_SUPPORT */
 
 /**
  * \brief           Return information associated with the given PK type
@@ -244,6 +246,7 @@
  */
 int pk_init_ctx( pk_context *ctx, const pk_info_t *info );
 
+#if defined(POLARSSL_PK_RSA_ALT_SUPPORT)
 /**
  * \brief           Initialize an RSA-alt context
  *
@@ -262,6 +265,7 @@
                          pk_rsa_alt_decrypt_func decrypt_func,
                          pk_rsa_alt_sign_func sign_func,
                          pk_rsa_alt_key_len_func key_len_func );
+#endif /* POLARSSL_PK_RSA_ALT_SUPPORT */
 
 /**
  * \brief           Get the size in bits of the underlying key
diff --git a/include/mbedtls/pk_wrap.h b/include/mbedtls/pk_wrap.h
index 3677250..7a7f4fa 100644
--- a/include/mbedtls/pk_wrap.h
+++ b/include/mbedtls/pk_wrap.h
@@ -33,6 +33,7 @@
 
 #include "pk.h"
 
+#if defined(POLARSSL_PK_RSA_ALT_SUPPORT)
 /* Container for RSA-alt */
 typedef struct
 {
@@ -41,6 +42,7 @@
     pk_rsa_alt_sign_func sign_func;
     pk_rsa_alt_key_len_func key_len_func;
 } rsa_alt_context;
+#endif
 
 #if defined(POLARSSL_RSA_C)
 extern const pk_info_t rsa_info;
@@ -55,6 +57,8 @@
 extern const pk_info_t ecdsa_info;
 #endif
 
+#if defined(POLARSSL_PK_RSA_ALT_SUPPORT)
 extern const pk_info_t rsa_alt_info;
+#endif
 
 #endif /* POLARSSL_PK_WRAP_H */