Index: includes/parser/Parser.php
===================================================================
--- includes/parser/Parser.php	(revision 88331)
+++ includes/parser/Parser.php	(working copy)
@@ -1155,8 +1155,8 @@
 				(<a[ \t\r\n>].*?</a>) |     # m[1]: Skip link text
 				(<.*?>) |                   # m[2]: Skip stuff inside HTML elements' . "
 				(\\b(?:$prots)$urlChar+) |  # m[3]: Free external links" . '
-				(?:RFC|PMID)\s+([0-9]+) |   # m[4]: RFC or PMID, capture number
-				ISBN\s+(\b                  # m[5]: ISBN, capture number
+				(?:RFC|PMID)\ +([0-9]+) |   # m[4]: RFC or PMID, capture number
+				ISBN\ +(\b                  # m[5]: ISBN, capture number
 					(?: 97[89] [\ \-]? )?   # optional 13-digit ISBN prefix
 					(?: [0-9]  [\ \-]? ){9} # 9 digits with opt. delimiters
 					[0-9Xx]                 # check digit