diff --git a/src/backend/tsearch/regis.c b/src/backend/tsearch/regis.c
index 4c35afd18d..0fe0064fd1 100644
--- a/src/backend/tsearch/regis.c
+++ b/src/backend/tsearch/regis.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/tsearch/regis.c,v 1.3 2008/01/01 19:45:52 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/tsearch/regis.c,v 1.4 2008/01/21 02:46:10 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -17,27 +17,59 @@
 #include "tsearch/dicts/regis.h"
 #include "tsearch/ts_locale.h"
 
-bool
-RS_isRegis(const char *str)
-{
-	while (str && *str)
-	{
-		if (t_isalpha(str) ||
-			t_iseq(str, '[') ||
-			t_iseq(str, ']') ||
-			t_iseq(str, '^'))
-			str += pg_mblen(str);
-		else
-			return false;
-	}
-	return true;
-}
-
 #define RS_IN_ONEOF 1
 #define RS_IN_ONEOF_IN	2
 #define RS_IN_NONEOF	3
 #define RS_IN_WAIT	4
 
+
+/*
+ * Test whether a regex is of the subset supported here.
+ * Keep this in sync with RS_compile!
+ */
+bool
+RS_isRegis(const char *str)
+{
+	int			state = RS_IN_WAIT;
+	const char *c = str;
+
+	while (*c)
+	{
+		if (state == RS_IN_WAIT)
+		{
+			if (t_isalpha(c))
+				/* okay */ ;
+			else if (t_iseq(c, '['))
+				state = RS_IN_ONEOF;
+			else
+				return false;
+		}
+		else if (state == RS_IN_ONEOF)
+		{
+			if (t_iseq(c, '^'))
+				state = RS_IN_NONEOF;
+			else if (t_isalpha(c))
+				state = RS_IN_ONEOF_IN;
+			else
+				return false;
+		}
+		else if (state == RS_IN_ONEOF_IN || state == RS_IN_NONEOF)
+		{
+			if (t_isalpha(c))
+				/* okay */ ;
+			else if (t_iseq(c, ']'))
+				state = RS_IN_WAIT;
+			else
+				return false;
+		}
+		else
+			elog(ERROR, "internal error in RS_isRegis: state %d", state);
+		c += pg_mblen(c);
+	}
+
+	return (state == RS_IN_WAIT);
+}
+
 static RegisNode *
 newRegisNode(RegisNode *prev, int len)
 {
@@ -50,11 +82,11 @@ newRegisNode(RegisNode *prev, int len)
 }
 
 void
-RS_compile(Regis *r, bool issuffix, char *str)
+RS_compile(Regis *r, bool issuffix, const char *str)
 {
 	int			len = strlen(str);
 	int			state = RS_IN_WAIT;
-	char	   *c = (char *) str;
+	const char *c = str;
 	RegisNode  *ptr = NULL;
 
 	memset(r, 0, sizeof(Regis));
@@ -83,11 +115,8 @@ RS_compile(Regis *r, bool issuffix, char *str)
 				ptr->type = RSF_ONEOF;
 				state = RS_IN_ONEOF;
 			}
-			else
-				ereport(ERROR,
-						(errcode(ERRCODE_INVALID_REGULAR_EXPRESSION),
-						 errmsg("invalid regis pattern: \"%s\"",
-								str)));
+			else				/* shouldn't get here */
+				elog(ERROR, "invalid regis pattern: \"%s\"", str);
 		}
 		else if (state == RS_IN_ONEOF)
 		{
@@ -102,11 +131,8 @@ RS_compile(Regis *r, bool issuffix, char *str)
 				ptr->len = pg_mblen(c);
 				state = RS_IN_ONEOF_IN;
 			}
-			else
-				ereport(ERROR,
-						(errcode(ERRCODE_INVALID_REGULAR_EXPRESSION),
-						 errmsg("invalid regis pattern: \"%s\"",
-								str)));
+			else				/* shouldn't get here */
+				elog(ERROR, "invalid regis pattern: \"%s\"", str);
 		}
 		else if (state == RS_IN_ONEOF_IN || state == RS_IN_NONEOF)
 		{
@@ -117,17 +143,17 @@ RS_compile(Regis *r, bool issuffix, char *str)
 			}
 			else if (t_iseq(c, ']'))
 				state = RS_IN_WAIT;
-			else
-				ereport(ERROR,
-						(errcode(ERRCODE_INVALID_REGULAR_EXPRESSION),
-						 errmsg("invalid regis pattern: \"%s\"",
-								str)));
+			else				/* shouldn't get here */
+				elog(ERROR, "invalid regis pattern: \"%s\"", str);
 		}
 		else
 			elog(ERROR, "internal error in RS_compile: state %d", state);
 		c += pg_mblen(c);
 	}
 
+	if (state != RS_IN_WAIT)		/* shouldn't get here */
+		elog(ERROR, "invalid regis pattern: \"%s\"", str);
+
 	ptr = r->node;
 	while (ptr)
 	{
diff --git a/src/backend/tsearch/spell.c b/src/backend/tsearch/spell.c
index 00f9d3c477..a2837d1683 100644
--- a/src/backend/tsearch/spell.c
+++ b/src/backend/tsearch/spell.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/tsearch/spell.c,v 1.10 2008/01/16 13:01:03 teodor Exp $
+ *	  $PostgreSQL: pgsql/src/backend/tsearch/spell.c,v 1.11 2008/01/21 02:46:10 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -333,7 +333,7 @@ NIAddAffix(IspellDict *Conf, int flag, char flagflags, const char *mask, const c
 		Affix->issimple = 0;
 		Affix->isregis = 1;
 		RS_compile(&(Affix->reg.regis), (type == FF_SUFFIX) ? true : false,
-				   (char *) ((mask && *mask) ? mask : VoidString));
+				   (mask && *mask) ? mask : VoidString);
 	}
 	else
 	{
diff --git a/src/include/tsearch/dicts/regis.h b/src/include/tsearch/dicts/regis.h
index b97ec25471..5c3c1794b8 100644
--- a/src/include/tsearch/dicts/regis.h
+++ b/src/include/tsearch/dicts/regis.h
@@ -6,7 +6,7 @@
  *
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  *
- * $PostgreSQL: pgsql/src/include/tsearch/dicts/regis.h,v 1.4 2008/01/01 19:45:59 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/tsearch/dicts/regis.h,v 1.5 2008/01/21 02:46:11 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -40,7 +40,7 @@ typedef struct Regis
 
 bool		RS_isRegis(const char *str);
 
-void		RS_compile(Regis *r, bool issuffix, char *str);
+void		RS_compile(Regis *r, bool issuffix, const char *str);
 void		RS_free(Regis *r);
 
 /*returns true if matches */