diff --git a/contrib/pgcrypto/px.c b/contrib/pgcrypto/px.c
index 4205e9c3ef..f7d9fb04ea 100644
--- a/contrib/pgcrypto/px.c
+++ b/contrib/pgcrypto/px.c
@@ -200,7 +200,7 @@ combo_init(PX_Combo *cx, const uint8 *key, unsigned klen,
 		ivbuf = palloc0(ivs);
 		if (ivlen > ivs)
 			memcpy(ivbuf, iv, ivs);
-		else
+		else if (ivlen != 0)
 			memcpy(ivbuf, iv, ivlen);
 	}
 
diff --git a/src/backend/access/transam/clog.c b/src/backend/access/transam/clog.c
index de787c3d37..30b7badcab 100644
--- a/src/backend/access/transam/clog.c
+++ b/src/backend/access/transam/clog.c
@@ -295,6 +295,7 @@ TransactionIdSetPageStatus(TransactionId xid, int nsubxids,
 	 * on the same page.  Check those conditions, too.
 	 */
 	if (all_xact_same_page && xid == MyProc->xid &&
+		nsubxids != 0 &&
 		nsubxids <= THRESHOLD_SUBTRANS_CLOG_OPT &&
 		nsubxids == MyProc->subxidStatus.count &&
 		memcmp(subxids, MyProc->subxids.xids,
diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index e5cf1bde13..428236da7f 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -1182,7 +1182,8 @@ DefineIndex(Oid relationId,
 			pgstat_progress_update_param(PROGRESS_CREATEIDX_PARTITIONS_TOTAL,
 										 nparts);
 
-			memcpy(part_oids, partdesc->oids, sizeof(Oid) * nparts);
+			if (nparts != 0)
+				memcpy(part_oids, partdesc->oids, sizeof(Oid) * nparts);
 
 			parentDesc = RelationGetDescr(rel);
 			opfamOids = palloc(sizeof(Oid) * numberOfKeyAttributes);