diff --git a/programs/ssl/ssl_server2.c b/programs/ssl/ssl_server2.c
index 42fa8d6..639fe56 100644
--- a/programs/ssl/ssl_server2.c
+++ b/programs/ssl/ssl_server2.c
@@ -58,6 +58,9 @@
 #endif
 
 #include "mbedtls/pk.h"
+#if defined(MBEDTLS_PK_HAVE_PRIVATE_HEADER)
+#include <mbedtls/private/pk_private.h>
+#endif /* MBEDTLS_PK_HAVE_PRIVATE_HEADER */
 
 /* Size of memory to be allocated for the heap, when using the library's memory
  * management and MBEDTLS_MEMORY_BUFFER_ALLOC_C is enabled. */