diff --git a/programs/pkey/gen_key.c b/programs/pkey/gen_key.c
index 4d329f2..94604ce 100644
--- a/programs/pkey/gen_key.c
+++ b/programs/pkey/gen_key.c
@@ -25,6 +25,9 @@
 #else
 
 #include "mbedtls/pk.h"
+#if defined(MBEDTLS_PK_HAVE_PRIVATE_HEADER)
+#include <mbedtls/private/pk_private.h>
+#endif /* MBEDTLS_PK_HAVE_PRIVATE_HEADER */
 #include "mbedtls/ecdsa.h"
 #include "mbedtls/rsa.h"
 #include "mbedtls/entropy.h"