diff --git a/rastertosag-gdi b/rastertosag-gdi
index 52b08d7..28f8606 100755
--- a/rastertosag-gdi
+++ b/rastertosag-gdi
@@ -1,4 +1,4 @@
-#!/usr/bin/python -u
+#!/usr/bin/python3 -u
 #coding=utf8
 
 # CUPS raster filter for Ricoh Aficio SP1000s
@@ -26,10 +26,10 @@
 if len(sys.argv)>6:
     filename=sys.argv[6]
 if filename=='.' or filename=='-':
-    input=sys.stdin
+    input=sys.stdin.buffer
 else:
-    input = open(sys.argv[6],'r')
-output = sys.stdout
+    input = open(sys.argv[6],'rb')
+output = sys.stdout.buffer
 
 def print_stderr(s,newline=True):
     sys.stderr.write(str(s)+('\n' if newline else ''))
@@ -39,7 +39,7 @@
 cups = input.read() # Read all bytes from stdin
 
 sync_word=cups[0:4] # length of sync-word is 4 bytes: "3SaR"
-version=int(cups[0])
+version=cups[0]-48
 cups=cups[4:]
 
 dtype={
@@ -55,7 +55,7 @@
 }
 
 def make_unpack_format(format,begin,end,split_count=1):
-    return '<'+(str((end-begin+1)/dtype[format]['size']/split_count)+dtype[format]['b'])*split_count
+    return '<'+(str((end-begin+1)//dtype[format]['size']//split_count)+dtype[format]['b'])*split_count
 
 hdr={
     1: {}, # version 1 header
@@ -159,10 +159,10 @@
     line=unpack('<'+str(numbytes)+'B',page_data[y*numbytes:(y+1)*numbytes])
     ret=[]
     extend=ret.extend
-    for x in range(0,w/8):
+    for x in range(0,w//8):
         extend(bytes[line[x]])
     if w%8:
-        extend(bytes[line[w/8]][:w%8])
+        extend(bytes[line[w//8]][:w%8])
     return ret
 
 FORMAT_WIDTH=0
@@ -185,7 +185,7 @@
 def begin_document():
     output.write(pack(
         '>76sbbHHI',
-        ') SAG-GDI RL;0;0;Comment Copyright Sagem Communication 2005. Version 1.0.0.0',
+        b') SAG-GDI RL;0;0;Comment Copyright Sagem Communication 2005. Version 1.0.0.0',
         0x0D,0x0A,
         0x1000,0x0200,
         0
@@ -217,7 +217,7 @@
 current_line_length=0
 def begin_block():
     global current_block_data
-    current_block_data=''
+    current_block_data=b''
 
 def get_block_size():
     return len(current_block_data)
@@ -232,7 +232,7 @@
     color = 1 if col else 0
     color_bit = color << 6
     first_byte = length%64
-    second_byte = length/64
+    second_byte = length//64
     two_bytes_bit = 0b10000000 if second_byte else 0b00000000
     
     px_data=pack('>B', two_bytes_bit | color_bit | first_byte)
@@ -257,7 +257,7 @@
     w,h=min(hdr[1]['cupsWidth'],formats[format][FORMAT_WIDTH]),min(hdr[1]['cupsHeight'],formats[format][FORMAT_HEIGHT])
     t=time()
     for y in range(h):
-        if y%(h/15)==0:
+        if y%(h//15)==0:
             print_stderr('%d%% '%(int(float(y)/h*100),),False)
 
         yline=get_cups_line(y)