diff --git a/Build.PL b/Build.PL
index 205b99e..d281a90 100755
--- a/Build.PL
+++ b/Build.PL
@@ -9,7 +9,6 @@ my $build = Module::Build->new(
     dist_author   => 'Sergio Iglesias <contact@owlcode.tech>',
     dist_abstract => 'Ruby/Sapphire save editor lib.',
     requires      => {
-        'Inline::C' => 0,
     },
 );
 $build->create_build_script;
diff --git a/lib/Rsaves.pm b/lib/Rsaves.pm
index 7fd0203..337ee38 100644
--- a/lib/Rsaves.pm
+++ b/lib/Rsaves.pm
@@ -409,7 +409,7 @@ sub _pokemon_checksum_substructures_fh {
     for ( 0 .. 3 ) {
         for ( 0 .. 5 ) {
             read $fh, my $read, 2 or die "Unable to read";
-            $checksum = _sum_u16( ( unpack 'v', $read ), $checksum );
+            $checksum = 0xffff & (( unpack 'v', $read ) + $checksum );
         }
     }
     return $checksum;
@@ -674,18 +674,6 @@ sub _decrypt_pokemon_substructures_raw {
     read $fh, my $read, 1 and die "Not all read";
     close $fh;
     open $fh, '<', \$result;
-
-#    my @order_substructures = _pokemon_substructures_order_by_modulo($personality % 24);
-#    for my $substruct_n (0..3) {
-#        my $offset = $substruct_n * 12;
-#        seek $fh, $substruct_n * 12, 0;
-#        for (0..5) {
-#            read $fh, my $read, 2 or die "Unable to read";
-#            $read = unpack 'v', $read;
-#            $compare_checksum = _sum_u16($read, $compare_checksum);
-#        }
-#    }
-#
     my $compare_checksum = _pokemon_checksum_substructures_fh($fh);
     die "Checksum $compare_checksum not equal to $checksum"
       if $compare_checksum != $checksum;
@@ -1024,27 +1012,12 @@ sub _recalculate_checksum {
         my $readed = '';
         read $fh, $readed, 4;
         my $to_add = unpack 'V', $readed;
-        $checksum = _sum_u32( $checksum, $to_add );
+        $checksum = 0xffffffff & ($checksum + $to_add);
     }
-    my $final_checksum = _sum_u32_to_u16( $checksum, $checksum >> 16 );
+    my $final_checksum = (_hihalf_u32($checksum) + _lowhalf_u32($checksum)) & 0xffffffff;
     $section->{checksum} = $final_checksum;
 }
 
-use Inline C => <<'EOF';
-unsigned int
-_sum_u32(unsigned int a, unsigned int b) {
-    return a + b;
-}
-unsigned short 
-_sum_u32_to_u16(unsigned int a, unsigned int b) {
-    return (short) a + b;
-}
-unsigned short
-_sum_u16(unsigned short a, unsigned short b) {
-    return (unsigned short) a + b;
-}
-EOF
-
 sub _find_section_save {
     my $save       = shift;
     my $section_id = shift;