diff --git a/src/backends/meta-monitor.c b/src/backends/meta-monitor.c
index 8f56e794b..9d2ed7f85 100644
--- a/src/backends/meta-monitor.c
+++ b/src/backends/meta-monitor.c
@@ -104,7 +104,7 @@ static void
 meta_monitor_mode_free (MetaMonitorMode *mode);
 
 MetaMonitorSpec *
-meta_monitor_spec_clone (MetaMonitorSpec *monitor_spec)
+meta_monitor_spec_clone (const MetaMonitorSpec *monitor_spec)
 {
   MetaMonitorSpec *new_monitor_spec;
 
diff --git a/src/backends/meta-monitor.h b/src/backends/meta-monitor.h
index b60f37f5a..8db517848 100644
--- a/src/backends/meta-monitor.h
+++ b/src/backends/meta-monitor.h
@@ -283,7 +283,7 @@ META_EXPORT_TEST
 gboolean meta_monitor_mode_should_be_advertised (MetaMonitorMode *monitor_mode);
 
 META_EXPORT_TEST
-MetaMonitorSpec * meta_monitor_spec_clone (MetaMonitorSpec *monitor_id);
+MetaMonitorSpec * meta_monitor_spec_clone (const MetaMonitorSpec *monitor_id);
 
 guint meta_monitor_spec_hash (gconstpointer key);