Index: source/alias.c
===================================================================
RCS file: /home/cvs/ircii/source/alias.c,v
retrieving revision 1.173
diff -p -u -r1.173 alias.c
--- source/alias.c	12 Dec 2016 19:54:29 -0000	1.173
+++ source/alias.c	29 Jan 2017 00:34:52 -0000
@@ -591,6 +591,28 @@ lastop(u_char *ptr)
 	return ptr;
 }
 
+/* Convert foo[bar][baz] into foo.bar.baz. */
+static	u_char	*
+bracket_to_dot(u_char *ptr)
+{
+	u_char	*left, *right, *s;
+
+	while ((left = my_index(ptr, '[')) != NULL)
+	{
+		*left++ = '.';
+		if ((right = matching_bracket(left, '[', ']')) != NULL)
+		{
+			*right++ = '\0';
+			/* can't use strcat here, overlapping strings */
+			for (s = ptr; *right; s++, right++)
+				*s++ = *right;
+		}
+		else
+			break;
+	}
+	return ptr;
+}
+
 #define	NU_EXPR	0
 #define	NU_CONJ NU_EXPR
 #define	NU_ASSN	1
@@ -645,7 +667,7 @@ next_unit(u_char *str, u_char *args, int
 			got_sloshed = 0;
 			continue;
 		}
-		switch(*ptr)
+		switch (*ptr)
 		{
 		case '\\':
 			got_sloshed = 1;
@@ -1010,9 +1032,6 @@ next_unit(u_char *str, u_char *args, int
 		case '=':
 			if (ptr[1] != '=')
 			{
-				u_char	*left_bracket,
-					*right_bracket;
-
 				if (stage != NU_ASSN)
 				{
 					ptr = lastop(ptr);
@@ -1026,20 +1045,9 @@ next_unit(u_char *str, u_char *args, int
 				lastc = result1 + my_strlen(result1) - 1;
 				while (lastc > result1 && *lastc == ' ')
 					*lastc-- = '\0';
-				for (ptr = result1; *ptr == ' '; ptr++);
-				while ((left_bracket = my_index(ptr, '['))
-						!= NULL)
-				{
-					*left_bracket++='.';
-					if ((right_bracket = matching_bracket(
-					    left_bracket, '[', ']')) != NULL)
-					{
-						*right_bracket++ = '\0';
-						my_strcat(ptr, right_bracket);
-					}
-					else
-						break;
-				}
+				for (ptr = result1; *ptr == ' '; ptr++)
+					/* nothing */;
+				bracket_to_dot(ptr);
 				if (*ptr)
 					add_alias(VAR_ALIAS, ptr, result2);
 				else