diff --git a/lib/ext/boot.c b/lib/ext/boot.c
index bfd25463..36d5828a 100644
--- a/lib/ext/boot.c
+++ b/lib/ext/boot.c
@@ -236,8 +236,10 @@ static const char boot_rom[][80] = {
 "        ,@(map (lambda (x)\n                  `(,(the 'define-syntax) ,(car x) ,(",
 "cadr x)))\n                formal)\n         ,@body))))\n\n(define-macro let-syntax\n",
 "  (lambda (form env)\n    `(,(the 'letrec-syntax) ,@(cdr form))))\n",
+"",
 };
 
+
 #if PIC_USE_LIBRARY
 static const char boot_library_rom[][80] = {
 ";;; There are two ways to name a library: (foo bar) or foo.bar\n;;; The former is",
@@ -367,7 +369,9 @@ static const char boot_library_rom[][80] = {
 " ((e eval))\n          (lambda (expr . lib)\n            (let ((lib (if (null? lib",
 ") (current-library) (car lib))))\n              (e expr (library-environment lib)",
 ")))))\n  (make-library '(picrin user))\n  (current-library '(picrin user)))\n\n",
+"",
 };
+
 #endif
 
 void
diff --git a/tools/mkboot.pl b/tools/mkboot.pl
index e5d31ff4..17b1fa4f 100644
--- a/tools/mkboot.pl
+++ b/tools/mkboot.pl
@@ -2,57 +2,39 @@
 
 use strict;
 
-# The maximum length of a string literal is 509 characters in C89.
-# That is why the boot_rom is split into short strings.
-my $chunk = 80;
-
-sub print_escape_char($) {
-    my $c = shift;
-    if ($c eq "\n") {
-        print "\\", "n";
-    } elsif (($c eq "\\") || ($c eq '"')) {
-        print "\\", $c;
-    } else {
-        print $c;
+sub constant($$) {
+    # The maximum length of a string literal is 509 characters in C89.
+    # That is why src is split into short strings.
+    my ($var, $src) = @_;
+    print "static const char ${var}[][80] = {\n";
+    my @lines = $src =~ /.{0,80}/gs;
+    foreach (@lines) {
+        s/\\/\\\\/g;
+        s/"/\\"/g;
+        s/\n/\\n/g;
+        print "\"$_\",\n";
     }
+    print "};\n\n";
 }
 
+local $/ = undef;
+
 print <<EOL;
 #include "picrin.h"
 #include "picrin/extra.h"
 
-static const char boot_rom[][$chunk] = {
 EOL
-print "\"";
-my $len = 0;
 open(IN, "piclib/boot.scm");
-while (read(IN, my $c, 1)) {
-    if ($len && ($len % $chunk == 0)) { print "\",\n\""; }
-    print_escape_char($c);
-    $len++;
-}
-if ($!) { die "read error"; }
+constant("boot_rom", <IN>);
 close(IN);
 print <<EOL;
-",
-};
 
 #if PIC_USE_LIBRARY
-static const char boot_library_rom[][$chunk] = {
 EOL
-print "\"";
-my $len = 0;
 open(IN, "piclib/library.scm");
-while (read(IN, my $c, 1)) {
-    if ($len && ($len % $chunk == 0)) { print "\",\n\""; }
-    print_escape_char($c);
-    $len++;
-}
-if ($!) { die "read error"; }
+constant("boot_library_rom", <IN>);
 close(IN);
 print <<EOL;
-",
-};
 #endif
 
 void
diff --git a/tools/mkloader.pl b/tools/mkloader.pl
index b87c3aef..34011174 100644
--- a/tools/mkloader.pl
+++ b/tools/mkloader.pl
@@ -3,6 +3,21 @@
 use strict;
 use File::Basename qw/basename dirname/;
 
+sub constant($$) {
+    # The maximum length of a string literal is 509 characters in C89.
+    # That is why src is split into short strings.
+    my ($var, $src) = @_;
+    print "static const char ${var}[][80] = {\n";
+    my @lines = $src =~ /.{0,80}/gs;
+    foreach (@lines) {
+        s/\\/\\\\/g;
+        s/"/\\"/g;
+        s/\n/\\n/g;
+        print "\"$_\",\n";
+    }
+    print "};\n\n";
+}
+
 print <<EOL;
 /**
  *                                !!NOTICE!!
@@ -18,21 +33,13 @@
 
 foreach my $file (@ARGV) {
     my $var = &escape_v($file);
-    print "static const char ${var}[][80] = {\n";
 
     open IN, $file;
     local $/ = undef;
     my $src = <IN>;
     close IN;
 
-    my @lines = $src =~ /.{0,80}/gs;
-    foreach (@lines) {
-        s/\\/\\\\/g;
-        s/"/\\"/g;
-        s/\n/\\n/g;
-        print "\"$_\",\n";
-    }
-    print "};\n\n";
+    constant($var, $src);
 }
 
 print <<EOL;