diff --git a/arm/makefile b/arm/Makefile
similarity index 100%
rename from arm/makefile
rename to arm/Makefile
diff --git a/arm/prog.py b/arm/prog.py
index df231c1..886d1af 100644
--- a/arm/prog.py
+++ b/arm/prog.py
@@ -28,10 +28,8 @@ def write(s, offset, dat):
 
 
 def jump(s, offset):
-        addr = struct.pack('<I', offset)
-
-        s.write(b'j')
-        s.write(addr)
+        cmd = struct.pack('<cI', b'j', offset)
+        s.write(cmd)
 
 
 def main():