diff --git a/src/testcurl/https/tls_test_common.h b/src/testcurl/https/tls_test_common.h
index b6a11172..a10f31e7 100644
--- a/src/testcurl/https/tls_test_common.h
+++ b/src/testcurl/https/tls_test_common.h
@@ -77,6 +77,9 @@ curl_check_version (const char *req_version, ...);
 int
 curl_tls_is_gnutls (void);
 
+int
+curl_tls_is_openssl (void);
+
 int
 curl_tls_is_nss (void);