--- src/parallel.orig	2011-08-22 07:17:43.000000000 +0800
+++ src/parallel	2011-08-22 23:51:57.455272434 +0800
@@ -4073,28 +4073,42 @@
 
 # Maximal command line length (for -m and -X)
 sub max_length {
-    # Find the max_length of a command line and cache it
-    # Returns:
-    #   number of chars on the longest command line allowed
+    # FreeBSD code:
     if(not $Limits::Command::line_max_len) {
-	if($::opt_s) {
-	    if(is_acceptable_command_line_length($::opt_s)) {
-		$Limits::Command::line_max_len = $::opt_s;
-	    } else {
-		# -s is too long: Find the correct
-		$Limits::Command::line_max_len = binary_find_max_length(0,$::opt_s);
+	$Limits::Command::line_max_len = `getconf ARG_MAX` - 1024;
+	if ($::opt_s) {
+	    if ($::opt_s > $Limits::Command::line_max_len) {
+	     print STDERR "$Global::progname: ",
+	     "you are setting value for -s greater than $Limits::Command::line_max_len\n";
 	    }
-	    if($::opt_s <= $Limits::Command::line_max_len) {
-		$Limits::Command::line_max_len = $::opt_s;
-	    } else {
-		print STDERR "$Global::progname: value for -s option ",
-		"should be < $Limits::Command::line_max_len\n";
-	    }
-	} else {
-	    $Limits::Command::line_max_len = real_max_length();
+	    $Limits::Command::line_max_len = $::opt_s;
 	}
     }
     return $Limits::Command::line_max_len;
+
+#    ORIGINAL code:
+#    # Find the max_length of a command line and cache it
+#    # Returns:
+#    #   number of chars on the longest command line allowed
+#    if(not $Limits::Command::line_max_len) {
+#	if($::opt_s) {
+#	    if(is_acceptable_command_line_length($::opt_s)) {
+#		$Limits::Command::line_max_len = $::opt_s;
+#	    } else {
+#		# -s is too long: Find the correct
+#		$Limits::Command::line_max_len = binary_find_max_length(0,$::opt_s);
+#	    }
+#	    if($::opt_s <= $Limits::Command::line_max_len) {
+#		$Limits::Command::line_max_len = $::opt_s;
+#	    } else {
+#		print STDERR "$Global::progname: value for -s option ",
+#		"should be < $Limits::Command::line_max_len\n";
+#	    }
+#	} else {
+#	    $Limits::Command::line_max_len = real_max_length();
+#	}
+#    }
+#    return $Limits::Command::line_max_len;
 }
 
 sub real_max_length {