diff --git a/gtk/gtkaccelgroup.c b/gtk/gtkaccelgroup.c
index e551505e19..2a861d23d6 100644
--- a/gtk/gtkaccelgroup.c
+++ b/gtk/gtkaccelgroup.c
@@ -933,7 +933,10 @@ gtk_accelerator_print_label (GString        *gstring,
       if (accelerator_key >= GDK_KEY_KP_Space &&
           accelerator_key <= GDK_KEY_KP_Equal)
         {
-          /* Translators: "KP" means "numeric key pad" */
+          /* Translators: "KP" means "numeric key pad". This string will
+           * be used in accelerators such as "Ctrl+Shift+KP 1" in menus,
+           * and therefore the translation needs to be very short.
+           */
           g_string_append (gstring, C_("keyboard label", "KP"));
           g_string_append (gstring, " ");
         }