diff --git a/src/acme.c b/src/acme.c
index a745884ef..e302b9865 100644
--- a/src/acme.c
+++ b/src/acme.c
@@ -1317,7 +1317,7 @@ int acme_req_finalize(struct task *task, struct acme_ctx *ctx, char **errmsg)
 	csr->data = ret;
 
 	chunk_printf(req_in, "{ \"csr\": \"%.*s\" }", (int)csr->data, csr->area);
-	free(data);
+	OPENSSL_free(data);
 
 
 	if (acme_jws_payload(req_in, ctx->nonce, ctx->finalize, ctx->cfg->account.pkey, ctx->kid, req_out, errmsg) != 0)