diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c
index 478e124..bff6f45 100644
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -2720,7 +2720,7 @@ postgresImportForeignSchema(ImportForeignSchemaStmt *stmt, Oid serverOid)
 					appendStringInfoString(&buf, ", ");
 				deparseStringLiteral(&buf, rv->relname);
 			}
-			appendStringInfoString(&buf, ")");
+			appendStringInfoChar(&buf, ')');
 		}
 
 		/* Append ORDER BY at the end of query to ensure output ordering */
@@ -2784,7 +2784,7 @@ postgresImportForeignSchema(ImportForeignSchemaStmt *stmt, Oid serverOid)
 				 */
 				appendStringInfoString(&buf, " OPTIONS (column_name ");
 				deparseStringLiteral(&buf, attname);
-				appendStringInfoString(&buf, ")");
+				appendStringInfoChar(&buf, ')');
 
 				/* Add COLLATE if needed */
 				if (import_collate && collname != NULL && collnamespace != NULL)
diff --git a/contrib/test_decoding/test_decoding.c b/contrib/test_decoding/test_decoding.c
index 963d5df..7ec00df 100644
--- a/contrib/test_decoding/test_decoding.c
+++ b/contrib/test_decoding/test_decoding.c
@@ -391,7 +391,7 @@ pg_decode_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 													  get_namespace_name(
 							  get_rel_namespace(RelationGetRelid(relation))),
 											  NameStr(class_form->relname)));
-	appendStringInfoString(ctx->out, ":");
+	appendStringInfoChar(ctx->out, ':');
 
 	switch (change->action)
 	{
diff --git a/src/backend/access/rmgrdesc/smgrdesc.c b/src/backend/access/rmgrdesc/smgrdesc.c
index 4ae08b1..56d02c3 100644
--- a/src/backend/access/rmgrdesc/smgrdesc.c
+++ b/src/backend/access/rmgrdesc/smgrdesc.c
@@ -29,7 +29,7 @@ smgr_desc(StringInfo buf, XLogReaderState *record)
 		xl_smgr_create *xlrec = (xl_smgr_create *) rec;
 		char	   *path = relpathperm(xlrec->rnode, xlrec->forkNum);
 
-		appendStringInfo(buf, "%s", path);
+		appendStringInfoString(buf, path);
 		pfree(path);
 	}
 	else if (info == XLOG_SMGR_TRUNCATE)
diff --git a/src/backend/access/rmgrdesc/xlogdesc.c b/src/backend/access/rmgrdesc/xlogdesc.c
index 2c432f3..4f29136 100644
--- a/src/backend/access/rmgrdesc/xlogdesc.c
+++ b/src/backend/access/rmgrdesc/xlogdesc.c
@@ -75,7 +75,7 @@ xlog_desc(StringInfo buf, XLogReaderState *record)
 	{
 		xl_restore_point *xlrec = (xl_restore_point *) rec;
 
-		appendStringInfo(buf, "%s", xlrec->rp_name);
+		appendStringInfoString(buf, xlrec->rp_name);
 	}
 	else if (info == XLOG_FPI || info == XLOG_FPI_FOR_HINT)
 	{
@@ -125,7 +125,7 @@ xlog_desc(StringInfo buf, XLogReaderState *record)
 		bool		fpw;
 
 		memcpy(&fpw, rec, sizeof(bool));
-		appendStringInfo(buf, "%s", fpw ? "true" : "false");
+		appendStringInfoString(buf, fpw ? "true" : "false");
 	}
 	else if (info == XLOG_END_OF_RECOVERY)
 	{
diff --git a/src/backend/catalog/namespace.c b/src/backend/catalog/namespace.c
index 1af977c..2f1c8bf 100644
--- a/src/backend/catalog/namespace.c
+++ b/src/backend/catalog/namespace.c
@@ -2936,7 +2936,7 @@ NameListToString(List *names)
 		if (IsA(name, String))
 			appendStringInfoString(&string, strVal(name));
 		else if (IsA(name, A_Star))
-			appendStringInfoString(&string, "*");
+			appendStringInfoChar(&string, '*');
 		else
 			elog(ERROR, "unexpected node type in name list: %d",
 				 (int) nodeTag(name));
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 29b5b1b..0115fbf 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -2176,7 +2176,7 @@ print_function_rettype(StringInfo buf, HeapTuple proctup)
 		appendStringInfoString(&rbuf, "TABLE(");
 		ntabargs = print_function_arguments(&rbuf, proctup, true, false);
 		if (ntabargs > 0)
-			appendStringInfoString(&rbuf, ")");
+			appendStringInfoChar(&rbuf, ')');
 		else
 			resetStringInfo(&rbuf);
 	}