diff --git a/src/backend/access/brin/brin_minmax_multi.c b/src/backend/access/brin/brin_minmax_multi.c
index bd14184d767..c62a3c8ba8c 100644
--- a/src/backend/access/brin/brin_minmax_multi.c
+++ b/src/backend/access/brin/brin_minmax_multi.c
@@ -3084,7 +3084,7 @@ brin_minmax_multi_summary_out(PG_FUNCTION_ARGS)
 
 		a = FunctionCall1(&fmgrinfo, ranges_deserialized->values[idx++]);
 
-		appendStringInfo(&str, "%s", DatumGetPointer(a));
+		appendStringInfoString(&str, DatumGetPointer(a));
 
 		b = cstring_to_text(str.data);
 
diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index ad3feb88b3b..4b600e951a5 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -783,18 +783,18 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
 					msgfmt = _(" %u pages from table (%.2f%% of total) had %lld dead item identifiers removed\n");
 
 					if (vacrel->nindexes == 0 || vacrel->num_index_scans == 0)
-						appendStringInfo(&buf, _("index scan not needed:"));
+						appendStringInfoString(&buf, _("index scan not needed:"));
 					else
-						appendStringInfo(&buf, _("index scan needed:"));
+						appendStringInfoString(&buf, _("index scan needed:"));
 				}
 				else
 				{
 					msgfmt = _(" %u pages from table (%.2f%% of total) have %lld dead item identifiers\n");
 
 					if (!vacrel->do_failsafe)
-						appendStringInfo(&buf, _("index scan bypassed:"));
+						appendStringInfoString(&buf, _("index scan bypassed:"));
 					else
-						appendStringInfo(&buf, _("index scan bypassed by failsafe:"));
+						appendStringInfoString(&buf, _("index scan bypassed by failsafe:"));
 				}
 				orig_rel_pages = vacrel->rel_pages + vacrel->pages_removed;
 				appendStringInfo(&buf, msgfmt,
diff --git a/src/bin/pg_amcheck/pg_amcheck.c b/src/bin/pg_amcheck/pg_amcheck.c
index 37103e18cbe..6b97d635c32 100644
--- a/src/bin/pg_amcheck/pg_amcheck.c
+++ b/src/bin/pg_amcheck/pg_amcheck.c
@@ -844,7 +844,7 @@ prepare_heap_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
 	if (opts.endblock >= 0)
 		appendPQExpBuffer(sql, ", endblock := " INT64_FORMAT, opts.endblock);
 
-	appendPQExpBuffer(sql, ")");
+	appendPQExpBufferChar(sql, ')');
 }
 
 /*
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index 195f8d8cd2d..2abf255798c 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -2934,7 +2934,7 @@ describeOneTableDetails(const char *schemaname,
 
 					if (has_some && !has_all)
 					{
-						appendPQExpBuffer(&buf, " (");
+						appendPQExpBufferStr(&buf, " (");
 
 						/* options */
 						if (has_ndistinct)
@@ -2954,7 +2954,7 @@ describeOneTableDetails(const char *schemaname,
 							appendPQExpBuffer(&buf, "%smcv", gotone ? ", " : "");
 						}
 
-						appendPQExpBuffer(&buf, ")");
+						appendPQExpBufferChar(&buf, ')');
 					}
 
 					appendPQExpBuffer(&buf, " ON %s FROM %s",
@@ -3577,7 +3577,7 @@ describeOneTableDetails(const char *schemaname,
 					child_relkind == RELKIND_PARTITIONED_INDEX)
 					appendPQExpBufferStr(&buf, ", PARTITIONED");
 				if (strcmp(PQgetvalue(result, i, 2), "t") == 0)
-					appendPQExpBuffer(&buf, " (DETACH PENDING)");
+					appendPQExpBufferStr(&buf, " (DETACH PENDING)");
 				if (i < tuples - 1)
 					appendPQExpBufferChar(&buf, ',');