diff --git a/chardev/char-pipe.c b/chardev/char-pipe.c
index 94d714f..fd12c9e 100644
--- a/chardev/char-pipe.c
+++ b/chardev/char-pipe.c
@@ -70,7 +70,7 @@
                               MAXCONNECT, NSENDBUF, NRECVBUF, NTIMEOUT, NULL);
     g_free(openname);
     if (s->file == INVALID_HANDLE_VALUE) {
-        error_setg(errp, "Failed CreateNamedPipe (%lu)", GetLastError());
+        error_setg_win32(errp, GetLastError(), "Failed CreateNamedPipe");
         s->file = NULL;
         goto fail;
     }
diff --git a/chardev/char-win.c b/chardev/char-win.c
index 34825f6..d4fb44c 100644
--- a/chardev/char-win.c
+++ b/chardev/char-win.c
@@ -96,7 +96,7 @@
     s->file = CreateFile(filename, GENERIC_READ | GENERIC_WRITE, 0, NULL,
                       OPEN_EXISTING, FILE_FLAG_OVERLAPPED, 0);
     if (s->file == INVALID_HANDLE_VALUE) {
-        error_setg(errp, "Failed CreateFile (%lu)", GetLastError());
+        error_setg_win32(errp, GetLastError(), "Failed CreateFile");
         s->file = NULL;
         goto fail;
     }