diff --git a/contrib/hstore/hstore_gist.c b/contrib/hstore/hstore_gist.c
index 102c9cea729..016bfa4a4c0 100644
--- a/contrib/hstore/hstore_gist.c
+++ b/contrib/hstore/hstore_gist.c
@@ -459,7 +459,7 @@ ghstore_picksplit(PG_FUNCTION_ARGS)
 			if (ISALLTRUE(datum_l) || ISALLTRUE(_j))
 			{
 				if (!ISALLTRUE(datum_l))
-					MemSet((void *) union_l, 0xff, siglen);
+					memset((void *) union_l, 0xff, siglen);
 			}
 			else
 			{
@@ -475,7 +475,7 @@ ghstore_picksplit(PG_FUNCTION_ARGS)
 			if (ISALLTRUE(datum_r) || ISALLTRUE(_j))
 			{
 				if (!ISALLTRUE(datum_r))
-					MemSet((void *) union_r, 0xff, siglen);
+					memset((void *) union_r, 0xff, siglen);
 			}
 			else
 			{
diff --git a/contrib/intarray/_intbig_gist.c b/contrib/intarray/_intbig_gist.c
index 18ecd8cda6b..c9d8f9b84dd 100644
--- a/contrib/intarray/_intbig_gist.c
+++ b/contrib/intarray/_intbig_gist.c
@@ -420,7 +420,7 @@ g_intbig_picksplit(PG_FUNCTION_ARGS)
 			if (ISALLTRUE(datum_l) || ISALLTRUE(_j))
 			{
 				if (!ISALLTRUE(datum_l))
-					MemSet((void *) union_l, 0xff, siglen);
+					memset((void *) union_l, 0xff, siglen);
 			}
 			else
 			{
@@ -436,7 +436,7 @@ g_intbig_picksplit(PG_FUNCTION_ARGS)
 			if (ISALLTRUE(datum_r) || ISALLTRUE(_j))
 			{
 				if (!ISALLTRUE(datum_r))
-					MemSet((void *) union_r, 0xff, siglen);
+					memset((void *) union_r, 0xff, siglen);
 			}
 			else
 			{
diff --git a/contrib/ltree/_ltree_gist.c b/contrib/ltree/_ltree_gist.c
index 72516c3b6b9..2dc59f8a0f0 100644
--- a/contrib/ltree/_ltree_gist.c
+++ b/contrib/ltree/_ltree_gist.c
@@ -345,7 +345,7 @@ _ltree_picksplit(PG_FUNCTION_ARGS)
 			if (LTG_ISALLTRUE(datum_l) || LTG_ISALLTRUE(_j))
 			{
 				if (!LTG_ISALLTRUE(datum_l))
-					MemSet((void *) union_l, 0xff, siglen);
+					memset((void *) union_l, 0xff, siglen);
 			}
 			else
 			{
@@ -361,7 +361,7 @@ _ltree_picksplit(PG_FUNCTION_ARGS)
 			if (LTG_ISALLTRUE(datum_r) || LTG_ISALLTRUE(_j))
 			{
 				if (!LTG_ISALLTRUE(datum_r))
-					MemSet((void *) union_r, 0xff, siglen);
+					memset((void *) union_r, 0xff, siglen);
 			}
 			else
 			{
diff --git a/contrib/oid2name/oid2name.c b/contrib/oid2name/oid2name.c
index a62a5eedb12..a3e358bb1be 100644
--- a/contrib/oid2name/oid2name.c
+++ b/contrib/oid2name/oid2name.c
@@ -424,7 +424,7 @@ sql_exec(PGconn *conn, const char *todo, bool quiet)
 		}
 		fprintf(stdout, "\n");
 		pad = (char *) pg_malloc(l + 1);
-		MemSet(pad, '-', l);
+		memset(pad, '-', l);
 		pad[l] = '\0';
 		fprintf(stdout, "%s\n", pad);
 		free(pad);
diff --git a/contrib/pg_trgm/trgm_gist.c b/contrib/pg_trgm/trgm_gist.c
index 6f28db7d1ed..7a7be807af1 100644
--- a/contrib/pg_trgm/trgm_gist.c
+++ b/contrib/pg_trgm/trgm_gist.c
@@ -914,7 +914,7 @@ gtrgm_picksplit(PG_FUNCTION_ARGS)
 			if (ISALLTRUE(datum_l) || cache[j].allistrue)
 			{
 				if (!ISALLTRUE(datum_l))
-					MemSet((void *) GETSIGN(datum_l), 0xff, siglen);
+					memset((void *) GETSIGN(datum_l), 0xff, siglen);
 			}
 			else
 			{
@@ -930,7 +930,7 @@ gtrgm_picksplit(PG_FUNCTION_ARGS)
 			if (ISALLTRUE(datum_r) || cache[j].allistrue)
 			{
 				if (!ISALLTRUE(datum_r))
-					MemSet((void *) GETSIGN(datum_r), 0xff, siglen);
+					memset((void *) GETSIGN(datum_r), 0xff, siglen);
 			}
 			else
 			{
diff --git a/src/backend/access/hash/hashovfl.c b/src/backend/access/hash/hashovfl.c
index e34cfc302d3..86aa48d520b 100644
--- a/src/backend/access/hash/hashovfl.c
+++ b/src/backend/access/hash/hashovfl.c
@@ -760,7 +760,7 @@ _hash_initbitmapbuffer(Buffer buf, uint16 bmsize, bool initpage)
 
 	/* set all of the bits to 1 */
 	freep = HashPageGetBitmap(pg);
-	MemSet(freep, 0xFF, bmsize);
+	memset(freep, 0xFF, bmsize);
 
 	/*
 	 * Set pd_lower just past the end of the bitmap page data.  We could even
diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index 9452932d590..3d37c1fe62e 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -1410,7 +1410,7 @@ pg_stat_get_wal_receiver(PG_FUNCTION_ARGS)
 		 * see details. Other users only get the pid value to know whether it
 		 * is a WAL receiver, but no details.
 		 */
-		MemSet(&nulls[1], true, sizeof(bool) * (tupdesc->natts - 1));
+		memset(&nulls[1], true, sizeof(bool) * (tupdesc->natts - 1));
 	}
 	else
 	{
diff --git a/src/backend/utils/adt/tsgistidx.c b/src/backend/utils/adt/tsgistidx.c
index b8fd96dd7b0..47daf8199ef 100644
--- a/src/backend/utils/adt/tsgistidx.c
+++ b/src/backend/utils/adt/tsgistidx.c
@@ -753,7 +753,7 @@ gtsvector_picksplit(PG_FUNCTION_ARGS)
 			if (ISALLTRUE(datum_l) || cache[j].allistrue)
 			{
 				if (!ISALLTRUE(datum_l))
-					MemSet((void *) GETSIGN(datum_l), 0xff, siglen);
+					memset((void *) GETSIGN(datum_l), 0xff, siglen);
 			}
 			else
 			{
@@ -769,7 +769,7 @@ gtsvector_picksplit(PG_FUNCTION_ARGS)
 			if (ISALLTRUE(datum_r) || cache[j].allistrue)
 			{
 				if (!ISALLTRUE(datum_r))
-					MemSet((void *) GETSIGN(datum_r), 0xff, siglen);
+					memset((void *) GETSIGN(datum_r), 0xff, siglen);
 			}
 			else
 			{