diff --git a/src/backend/executor/nodeWindowAgg.c b/src/backend/executor/nodeWindowAgg.c
index 81ba024bba..083a3b2386 100644
--- a/src/backend/executor/nodeWindowAgg.c
+++ b/src/backend/executor/nodeWindowAgg.c
@@ -2234,6 +2234,21 @@ ExecWindowAgg(PlanState *pstate)
 			if (winstate->numaggs > 0)
 				eval_windowaggregates(winstate);
 		}
+		else if (!winstate->top_window)
+		{
+			/*
+			 * Otherwise, if we're not the top-window, we'd better fill the
+			 * aggregate values in with something, else they might be pointing
+			 * to freed memory.  These don't need to be valid since WindowAggs
+			 * above us cannot reference the result of another WindowAgg.
+			 */
+			numfuncs = winstate->numfuncs;
+			for (i = 0; i < numfuncs; i++)
+			{
+				econtext->ecxt_aggvalues[i] = (Datum) 0;
+				econtext->ecxt_aggnulls[i] = true;
+			}
+		}
 
 		/*
 		 * If we have created auxiliary read pointers for the frame or group