diff --git a/src/backend/access/spgist/spgscan.c b/src/backend/access/spgist/spgscan.c
index 34983ee5a7..dbd68a3b24 100644
--- a/src/backend/access/spgist/spgscan.c
+++ b/src/backend/access/spgist/spgscan.c
@@ -451,10 +451,22 @@ spgNewHeapItem(SpGistScanOpaque so, int level, ItemPointer heapPtr,
 
 	item->level = level;
 	item->heapPtr = *heapPtr;
-	/* copy value to queue cxt out of tmp cxt */
-	item->value = isnull ? (Datum) 0 :
-		datumCopy(leafValue, so->state.attLeafType.attbyval,
-				  so->state.attLeafType.attlen);
+
+	/*
+	 * If we need the reconstructed value, copy it to queue cxt out of tmp
+	 * cxt.  Caution: the leaf_consistent method may not have supplied a value
+	 * if we didn't ask it to, and mildly-broken methods might supply one of
+	 * the wrong type.  Also, while the correct leafValue type is attType not
+	 * leafType, pre-v14 Postgres versions have historically used attLeafType
+	 * here; let's not confuse matters even more by changing that in a minor
+	 * release.
+	 */
+	if (so->want_itup)
+		item->value = isnull ? (Datum) 0 :
+			datumCopy(leafValue, so->state.attLeafType.attbyval,
+					  so->state.attLeafType.attlen);
+	else
+		item->value = (Datum) 0;
 	item->traversalValue = NULL;
 	item->isLeaf = true;
 	item->recheck = recheck;
diff --git a/src/backend/utils/adt/geo_spgist.c b/src/backend/utils/adt/geo_spgist.c
index 8e29770422..fb2e7b5720 100644
--- a/src/backend/utils/adt/geo_spgist.c
+++ b/src/backend/utils/adt/geo_spgist.c
@@ -749,8 +749,13 @@ spg_box_quad_leaf_consistent(PG_FUNCTION_ARGS)
 	/* All tests are exact. */
 	out->recheck = false;
 
-	/* leafDatum is what it is... */
-	out->leafValue = in->leafDatum;
+	/*
+	 * Don't return leafValue unless told to; this is used for both box and
+	 * polygon opclasses, and in the latter case the leaf datum is not even of
+	 * the right type to return.
+	 */
+	if (in->returnData)
+		out->leafValue = leaf;
 
 	/* Perform the required comparison(s) */
 	for (i = 0; i < in->nkeys; i++)