diff --git a/src/backends/meta-monitor.c b/src/backends/meta-monitor.c
index 9d2ed7f85..06c9ee829 100644
--- a/src/backends/meta-monitor.c
+++ b/src/backends/meta-monitor.c
@@ -131,8 +131,8 @@ meta_monitor_spec_hash (gconstpointer key)
 }
 
 gboolean
-meta_monitor_spec_equals (MetaMonitorSpec *monitor_spec,
-                          MetaMonitorSpec *other_monitor_spec)
+meta_monitor_spec_equals (const MetaMonitorSpec *monitor_spec,
+                          const MetaMonitorSpec *other_monitor_spec)
 {
   return (g_str_equal (monitor_spec->connector, other_monitor_spec->connector) &&
           g_str_equal (monitor_spec->vendor, other_monitor_spec->vendor) &&
diff --git a/src/backends/meta-monitor.h b/src/backends/meta-monitor.h
index 8db517848..c4e651750 100644
--- a/src/backends/meta-monitor.h
+++ b/src/backends/meta-monitor.h
@@ -288,8 +288,8 @@ MetaMonitorSpec * meta_monitor_spec_clone (const MetaMonitorSpec *monitor_id);
 guint meta_monitor_spec_hash (gconstpointer key);
 
 META_EXPORT_TEST
-gboolean meta_monitor_spec_equals (MetaMonitorSpec *monitor_id,
-                                   MetaMonitorSpec *other_monitor_id);
+gboolean meta_monitor_spec_equals (const MetaMonitorSpec *monitor_id,
+                                   const MetaMonitorSpec *other_monitor_id);
 
 META_EXPORT_TEST
 int meta_monitor_spec_compare (MetaMonitorSpec *monitor_spec_a,