diff --git a/gio/win32/gwin32fsmonitorutils.c b/gio/win32/gwin32fsmonitorutils.c
index 6901561b8..e16421702 100644
--- a/gio/win32/gwin32fsmonitorutils.c
+++ b/gio/win32/gwin32fsmonitorutils.c
@@ -237,8 +237,8 @@ g_win32_fs_monitor_callback (DWORD        error,
 
 void
 g_win32_fs_monitor_init (GWin32FSMonitorPrivate *monitor,
-                         gchar *dirname,
-                         gchar *filename,
+                         const gchar *dirname,
+                         const gchar *filename,
                          gboolean isfile)
 {
   wchar_t *wdirname_with_long_prefix = NULL;
diff --git a/gio/win32/gwin32fsmonitorutils.h b/gio/win32/gwin32fsmonitorutils.h
index 0606d671d..96e071639 100644
--- a/gio/win32/gwin32fsmonitorutils.h
+++ b/gio/win32/gwin32fsmonitorutils.h
@@ -63,8 +63,8 @@ enum GWin32FileMonitorFileAlias
 GWin32FSMonitorPrivate* g_win32_fs_monitor_create (gboolean isfile);
 
 void g_win32_fs_monitor_init (GWin32FSMonitorPrivate *monitor,
-                              gchar *dirname,
-                              gchar *filename,
+                              const gchar *dirname,
+                              const gchar *filename,
                               gboolean isfile);
 
 void g_win32_fs_monitor_finalize (GWin32FSMonitorPrivate *monitor);