diff --git a/Shorewall-perl/Shorewall/Config.pm b/Shorewall-perl/Shorewall/Config.pm
index 92c3887d1..3e616c998 100644
--- a/Shorewall-perl/Shorewall/Config.pm
+++ b/Shorewall-perl/Shorewall/Config.pm
@@ -866,8 +866,10 @@ sub read_a_line() {
 	    # Continuation
 	    #
 	    chop $currentline, next if substr( ( $currentline .= $_ ), -1, 1 ) eq '\\';
-
-	    $currentline =~ s/#.*$//;       # Remove Trailing Comments -- result might be a blank line
+	    #
+	    # Remove Trailing Comments -- result might be a blank line
+	    #
+	    $currentline =~ s/#.*$//;       
 	    #
 	    # Ignore ( concatenated ) Blank Lines
 	    #
@@ -875,11 +877,11 @@ sub read_a_line() {
 	    #
 	    # Expand Shell Variables using %ENV
 	    #
-	    while ( $currentline =~ m( ^(.*?)
-                                       \$({)?            
-                                       ([a-zA-Z]\w*)
-                                       (?(2)})
-                                       (.*)$)x
+	    while ( $currentline =~ m( ^(.*?)        #Part preceding '$'
+                                       \$({)?        #'$' and optional '{'
+                                       ([a-zA-Z]\w*) #Shell Variable Name
+                                       (?(2)})       #Match closing '}'
+                                       (.*)$)x       #Rest of Line
                                      ) {
 		my $val = $ENV{$3};
 		$val = '' unless defined $val;