diff --git a/tests/src/certs.c b/tests/src/certs.c
index d1af5b2..f7a73bf 100644
--- a/tests/src/certs.c
+++ b/tests/src/certs.c
@@ -12,6 +12,9 @@
 #include "mbedtls/build_info.h"
 
 #include "mbedtls/pk.h"
+#if defined(MBEDTLS_PK_HAVE_PRIVATE_HEADER)
+#include <mbedtls/private/pk_private.h>
+#endif /* MBEDTLS_PK_HAVE_PRIVATE_HEADER */
 
 #include "test/test_certs.h"