diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index 0ae5873..b5d6545 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -3808,6 +3808,17 @@ find_compatible_pertrans(AggState *aggstate, Aggref *newagg,
 {
 	ListCell   *lc;
 
+	/*
+	 * Don't attempt to share aggregate states between ordered-set aggregates.
+	 * Really this is a bit of a hack since some of the builtin ordered-set
+	 * aggregate's final functions are destructive to the transition state.
+	 * A proper fix for this would be to devise a method of allowing a final
+	 * function to know if it was the first or last final function to be
+	 * called on the aggregate state.
+	 */
+	if (newagg->aggkind == AGGKIND_HYPOTHETICAL)
+		return -1;
+
 	foreach(lc, transnos)
 	{
 		int			transno = lfirst_int(lc);