diff --git a/glib/gconvert.c b/glib/gconvert.c
index 5ec8f1d99..520c32abe 100644
--- a/glib/gconvert.c
+++ b/glib/gconvert.c
@@ -808,7 +808,7 @@ g_convert_with_fallback (const gchar *str,
 			 gssize       len,    
 			 const gchar *to_codeset,
 			 const gchar *from_codeset,
-			 gchar       *fallback,
+			 const gchar *fallback,
 			 gsize       *bytes_read,
 			 gsize       *bytes_written,
 			 GError     **error)
diff --git a/glib/gconvert.h b/glib/gconvert.h
index 4d767841d..c4f274fb9 100644
--- a/glib/gconvert.h
+++ b/glib/gconvert.h
@@ -79,7 +79,7 @@ gchar* g_convert_with_fallback (const gchar  *str,
 				gssize        len,            
 				const gchar  *to_codeset,
 				const gchar  *from_codeset,
-				gchar        *fallback,
+				const gchar  *fallback,
 				gsize        *bytes_read,     
 				gsize        *bytes_written,  
 				GError      **error) G_GNUC_MALLOC;