diff --git a/gdk/gdkcontentformats.c b/gdk/gdkcontentformats.c
index 52437c02fd..e83b1b783e 100644
--- a/gdk/gdkcontentformats.c
+++ b/gdk/gdkcontentformats.c
@@ -465,8 +465,8 @@ gdk_content_formats_contain_mime_type (const GdkContentFormats *formats,
  *     types included in @formats or %NULL if none.
  **/
 const GType *
-gdk_content_formats_get_gtypes (GdkContentFormats *formats,
-                                gsize             *n_gtypes)
+gdk_content_formats_get_gtypes (const GdkContentFormats *formats,
+                                gsize                   *n_gtypes)
 {
   g_return_val_if_fail (formats != NULL, NULL);
 
@@ -491,8 +491,8 @@ gdk_content_formats_get_gtypes (GdkContentFormats *formats,
  *     if none.
  **/
 const char * const *
-gdk_content_formats_get_mime_types (GdkContentFormats *formats,
-                                    gsize             *n_mime_types)
+gdk_content_formats_get_mime_types (const GdkContentFormats *formats,
+                                    gsize                   *n_mime_types)
 {
   g_return_val_if_fail (formats != NULL, NULL);
 
diff --git a/gdk/gdkcontentformats.h b/gdk/gdkcontentformats.h
index 2fe983ea19..1798c48284 100644
--- a/gdk/gdkcontentformats.h
+++ b/gdk/gdkcontentformats.h
@@ -52,10 +52,10 @@ GDK_AVAILABLE_IN_ALL
 char *                  gdk_content_formats_to_string           (GdkContentFormats              *formats);
 
 GDK_AVAILABLE_IN_ALL
-const GType *           gdk_content_formats_get_gtypes          (GdkContentFormats              *formats,
+const GType *           gdk_content_formats_get_gtypes          (const GdkContentFormats        *formats,
                                                                  gsize                          *n_gtypes);
 GDK_AVAILABLE_IN_ALL
-const char * const *    gdk_content_formats_get_mime_types      (GdkContentFormats              *formats,
+const char * const *    gdk_content_formats_get_mime_types      (const GdkContentFormats        *formats,
                                                                  gsize                          *n_mime_types);
 
 GDK_AVAILABLE_IN_ALL