diff --git a/contrib/seg/seg.c b/contrib/seg/seg.c
index aea86765568685b73e9d43e0548aa4075552801d..3354a90094278d0fe5a49d358960057325d5584d 100644
--- a/contrib/seg/seg.c
+++ b/contrib/seg/seg.c
@@ -426,7 +426,7 @@ gseg_picksplit(GistEntryVector *entryvec,
 		else
 		{
 			datum_r = union_dr;
-			size_r = size_alpha;
+			size_r = size_beta;
 			*right++ = i;
 			v->spl_nright++;
 		}