diff --git a/Shorewall/Perl/Shorewall/Chains.pm b/Shorewall/Perl/Shorewall/Chains.pm
index 803264193..cffb24b88 100644
--- a/Shorewall/Perl/Shorewall/Chains.pm
+++ b/Shorewall/Perl/Shorewall/Chains.pm
@@ -1262,7 +1262,7 @@ sub ensure_accounting_chain( $$ )
 	fatal_error "Non-accounting chain ($chain) used in an accounting rule" unless $chainref->{accounting};
     } else {
 	fatal_error "Chain name ($chain) too long" if length $chain > 29;
-	fatal_error "Invalid Chain name ($chain)" unless $chain =~ /^[-\w.]+$/;
+	fatal_error "Invalid Chain name ($chain)" unless $chain =~ /^[-\w]+$/;
 	$chainref = new_chain 'filter' , $chain;
 	$chainref->{accounting} = 1;
 	$chainref->{referenced} = 1;
@@ -1351,7 +1351,7 @@ sub new_nat_chain($) {
 sub new_manual_chain($) {
     my $chain = $_[0];
     fatal_error "Chain name ($chain) too long" if length $chain > 29;
-    fatal_error "Invalid Chain name ($chain)" unless $chain =~ /^[-\w.]+$/;
+    fatal_error "Invalid Chain name ($chain)" unless $chain =~ /^[-\w]+$/;
     fatal_error "Duplicate Chain Name ($chain)" if $targets{$chain} || $filter_table->{$chain};
     $targets{$chain} = CHAIN;
     ( my $chainref = ensure_filter_chain( $chain, 0) )->{manual} = 1;
diff --git a/manpages/shorewall-accounting.xml b/manpages/shorewall-accounting.xml
index e315bb0ad..f20f7f44b 100644
--- a/manpages/shorewall-accounting.xml
+++ b/manpages/shorewall-accounting.xml
@@ -74,7 +74,8 @@
                 role="bold">:COUNT</emphasis> is included, a counting rule
                 matching this entry will be added to
                 <emphasis>chain</emphasis>. The <emphasis>chain</emphasis> may
-                not exceed 29 characters in length.</para>
+                not exceed 29 characters in length and may be composed of
+                letters, digits, dash ('-') and underscore ('_').</para>
               </listitem>
             </varlistentry>
 
diff --git a/manpages6/shorewall6-accounting.xml b/manpages6/shorewall6-accounting.xml
index d8928d6fb..c9dcd7d64 100644
--- a/manpages6/shorewall6-accounting.xml
+++ b/manpages6/shorewall6-accounting.xml
@@ -74,7 +74,8 @@
                 role="bold">:COUNT</emphasis> is included, a counting rule
                 matching this entry will be added to
                 <emphasis>chain</emphasis>. The <emphasis>chain</emphasis> may
-                not exceed 29 characters in length.</para>
+                not exceed 29 characters in length and may be composed of
+                letters, digits, dash ('-') and underscore ('_').</para>
               </listitem>
             </varlistentry>