2 files changed, 6 insertions, 3 deletions
diff --git a/src/interfaces/libpq/fe-print.c b/src/interfaces/libpq/fe-print.c
index 8b403c678b3..0b6b17e8390 100644
--- a/src/interfaces/libpq/fe-print.c
+++ b/src/interfaces/libpq/fe-print.c
@@ -36,6 +36,7 @@
 #include "libpq-fe.h"
 #include "libpq-int.h"
 
+#define PQmblenBounded(s, e)  strnlen(s, PQmblen(s, e))
 
 static void do_field(const PQprintOpt *po, const PGresult *res,
 					 const int i, const int j, const int fs_len,
@@ -365,7 +366,7 @@ do_field(const PQprintOpt *po, const PGresult *res,
 			/* Detect whether field contains non-numeric data */
 			char		ch = '0';
 
-			for (p = pval; *p; p += PQmblen(p, res->client_encoding))
+			for (p = pval; *p; p += PQmblenBounded(p, res->client_encoding))
 			{
 				ch = *p;
 				if (!((ch >= '0' && ch <= '9') ||
diff --git a/src/interfaces/libpq/fe-protocol3.c b/src/interfaces/libpq/fe-protocol3.c
index 3bc569e1c00..c9f88ba1db9 100644
--- a/src/interfaces/libpq/fe-protocol3.c
+++ b/src/interfaces/libpq/fe-protocol3.c
@@ -41,6 +41,8 @@
 	((id) == 'T' || (id) == 'D' || (id) == 'd' || (id) == 'V' || \
 	 (id) == 'E' || (id) == 'N' || (id) == 'A')
 
+#define PQmblenBounded(s, e)  strnlen(s, PQmblen(s, e))
+
 
 static void handleSyncLoss(PGconn *conn, char id, int msgLength);
 static int	getRowDescriptions(PGconn *conn, int msgLength);
@@ -1245,7 +1247,7 @@ reportErrorPosition(PQExpBuffer msg, const char *query, int loc, int encoding)
 			if (w <= 0)
 				w = 1;
 			scroffset += w;
-			qoffset += pg_encoding_mblen(encoding, &wquery[qoffset]);
+			qoffset += PQmblenBounded(&wquery[qoffset], encoding);
 		}
 		else
 		{
@@ -1313,7 +1315,7 @@ reportErrorPosition(PQExpBuffer msg, const char *query, int loc, int encoding)
 		 * width.
 		 */
 		scroffset = 0;
-		for (; i < msg->len; i += pg_encoding_mblen(encoding, &msg->data[i]))
+		for (; i < msg->len; i += PQmblenBounded(&msg->data[i], encoding))
 		{
 			int			w = pg_encoding_dsplen(encoding, &msg->data[i]);