diff --git a/app/core/gimpimage-convert-indexed.c b/app/core/gimpimage-convert-indexed.c
index 22e6d1f7bd..0c03581f71 100644
--- a/app/core/gimpimage-convert-indexed.c
+++ b/app/core/gimpimage-convert-indexed.c
@@ -2361,6 +2361,8 @@ select_colors_gray (QuantizeObj *quantobj,
   /* Compute the representative color for each box, fill colormap */
   for (i = 0; i < numboxes; i++)
     compute_color_gray (quantobj, histogram, boxlist + i, i);
+
+  g_free (boxlist);
 }