diff --git a/contrib/ltree/lquery_op.c b/contrib/ltree/lquery_op.c
index d580339283..a6466f575f 100644
--- a/contrib/ltree/lquery_op.c
+++ b/contrib/ltree/lquery_op.c
@@ -25,17 +25,16 @@ static char *
 getlexeme(char *start, char *end, int *len)
 {
 	char	   *ptr;
-	int			charlen;
 
-	while (start < end && (charlen = pg_mblen(start)) == 1 && t_iseq(start, '_'))
-		start += charlen;
+	while (start < end && t_iseq(start, '_'))
+		start += pg_mblen(start);
 
 	ptr = start;
 	if (ptr >= end)
 		return NULL;
 
-	while (ptr < end && !((charlen = pg_mblen(ptr)) == 1 && t_iseq(ptr, '_')))
-		ptr += charlen;
+	while (ptr < end && !t_iseq(ptr, '_'))
+		ptr += pg_mblen(ptr);
 
 	*len = ptr - start;
 	return start;
diff --git a/contrib/ltree/ltree.h b/contrib/ltree/ltree.h
index 40aed0ca0c..2a80a02495 100644
--- a/contrib/ltree/ltree.h
+++ b/contrib/ltree/ltree.h
@@ -126,7 +126,7 @@ typedef struct
 
 #define LQUERY_HASNOT		0x01
 
-#define ISALNUM(x)	( t_isalpha(x) || t_isdigit(x)	|| ( pg_mblen(x) == 1 && t_iseq((x), '_') ) )
+#define ISALNUM(x)	( t_isalnum(x) || t_iseq(x, '_') )
 
 /* full text query */
 
diff --git a/contrib/ltree/ltxtquery_io.c b/contrib/ltree/ltxtquery_io.c
index 3eca5cb8ff..8ab0ce8e52 100644
--- a/contrib/ltree/ltxtquery_io.c
+++ b/contrib/ltree/ltxtquery_io.c
@@ -64,13 +64,13 @@ gettoken_query(QPRS_STATE *state, int32 *val, int32 *lenval, char **strval, uint
 		switch (state->state)
 		{
 			case WAITOPERAND:
-				if (charlen == 1 && t_iseq(state->buf, '!'))
+				if (t_iseq(state->buf, '!'))
 				{
 					(state->buf)++;
 					*val = (int32) '!';
 					return OPR;
 				}
-				else if (charlen == 1 && t_iseq(state->buf, '('))
+				else if (t_iseq(state->buf, '('))
 				{
 					state->count++;
 					(state->buf)++;
@@ -97,11 +97,11 @@ gettoken_query(QPRS_STATE *state, int32 *val, int32 *lenval, char **strval, uint
 								 errmsg("modifiers syntax error")));
 					*lenval += charlen;
 				}
-				else if (charlen == 1 && t_iseq(state->buf, '%'))
+				else if (t_iseq(state->buf, '%'))
 					*flag |= LVAR_SUBLEXEME;
-				else if (charlen == 1 && t_iseq(state->buf, '@'))
+				else if (t_iseq(state->buf, '@'))
 					*flag |= LVAR_INCASE;
-				else if (charlen == 1 && t_iseq(state->buf, '*'))
+				else if (t_iseq(state->buf, '*'))
 					*flag |= LVAR_ANYEND;
 				else
 				{
@@ -110,14 +110,14 @@ gettoken_query(QPRS_STATE *state, int32 *val, int32 *lenval, char **strval, uint
 				}
 				break;
 			case WAITOPERATOR:
-				if (charlen == 1 && (t_iseq(state->buf, '&') || t_iseq(state->buf, '|')))
+				if (t_iseq(state->buf, '&') || t_iseq(state->buf, '|'))
 				{
 					state->state = WAITOPERAND;
 					*val = (int32) *(state->buf);
 					(state->buf)++;
 					return OPR;
 				}
-				else if (charlen == 1 && t_iseq(state->buf, ')'))
+				else if (t_iseq(state->buf, ')'))
 				{
 					(state->buf)++;
 					state->count--;
@@ -125,7 +125,7 @@ gettoken_query(QPRS_STATE *state, int32 *val, int32 *lenval, char **strval, uint
 				}
 				else if (*(state->buf) == '\0')
 					return (state->count) ? ERR : END;
-				else if (charlen == 1 && !t_iseq(state->buf, ' '))
+				else if (!t_iseq(state->buf, ' '))
 					return ERR;
 				break;
 			default:
diff --git a/contrib/pg_trgm/trgm.h b/contrib/pg_trgm/trgm.h
index 405a1d9552..afb0adb222 100644
--- a/contrib/pg_trgm/trgm.h
+++ b/contrib/pg_trgm/trgm.h
@@ -52,7 +52,7 @@ typedef char trgm[3];
 } while(0)
 
 #ifdef KEEPONLYALNUM
-#define ISWORDCHR(c)	(t_isalpha(c) || t_isdigit(c))
+#define ISWORDCHR(c)	(t_isalnum(c))
 #define ISPRINTABLECHAR(a)	( isascii( *(unsigned char*)(a) ) && (isalnum( *(unsigned char*)(a) ) || *(unsigned char*)(a)==' ') )
 #else
 #define ISWORDCHR(c)	(!t_isspace(c))
diff --git a/src/backend/tsearch/ts_locale.c b/src/backend/tsearch/ts_locale.c
index e0aa570bf5..fc21bf9ee8 100644
--- a/src/backend/tsearch/ts_locale.c
+++ b/src/backend/tsearch/ts_locale.c
@@ -81,6 +81,22 @@ t_isalpha(const char *ptr)
 	return iswalpha((wint_t) character[0]);
 }
 
+int
+t_isalnum(const char *ptr)
+{
+	int			clen = pg_mblen(ptr);
+	wchar_t		character[WC_BUF_LEN];
+	Oid			collation = DEFAULT_COLLATION_OID;	/* TODO */
+	pg_locale_t mylocale = 0;	/* TODO */
+
+	if (clen == 1 || lc_ctype_is_c(collation))
+		return isalnum(TOUCHAR(ptr));
+
+	char2wchar(character, WC_BUF_LEN, ptr, clen, mylocale);
+
+	return iswalnum((wint_t) character[0]);
+}
+
 int
 t_isprint(const char *ptr)
 {
diff --git a/src/backend/utils/adt/tsquery.c b/src/backend/utils/adt/tsquery.c
index f49e6bb157..a206926042 100644
--- a/src/backend/utils/adt/tsquery.c
+++ b/src/backend/utils/adt/tsquery.c
@@ -248,7 +248,7 @@ parse_or_operator(TSQueryParserState pstate)
 		return false;
 
 	/* it shouldn't be a part of any word */
-	if (t_iseq(ptr, '-') || t_iseq(ptr, '_') || t_isalpha(ptr) || t_isdigit(ptr))
+	if (t_iseq(ptr, '-') || t_iseq(ptr, '_') || t_isalnum(ptr))
 		return false;
 
 	for (;;)
diff --git a/src/include/tsearch/ts_locale.h b/src/include/tsearch/ts_locale.h
index d14cb4ed26..10887290dc 100644
--- a/src/include/tsearch/ts_locale.h
+++ b/src/include/tsearch/ts_locale.h
@@ -42,6 +42,7 @@ typedef struct
 extern int	t_isdigit(const char *ptr);
 extern int	t_isspace(const char *ptr);
 extern int	t_isalpha(const char *ptr);
+extern int	t_isalnum(const char *ptr);
 extern int	t_isprint(const char *ptr);
 
 extern char *lowerstr(const char *str);