diff --git a/cpp/emulator.cpp b/cpp/emulator.cpp
index 1446b76..54b8d88 100644
--- a/cpp/emulator.cpp
+++ b/cpp/emulator.cpp
@@ -6,8 +6,8 @@
 #include <stdlib.h>
 
 int main(int argc, char *argv[]) {
-  std::ifstream f;
-  std::streamsize fsize;
+  std::ifstream bytecode_if;
+  std::streamsize bytecode_size;
   uint8_t * bytecode;
 
   if (argc < 2) {
@@ -18,14 +18,13 @@ int main(int argc, char *argv[]) {
   /*
   reading bytecode
   */
-  f.open(argv[1], std::ios::binary | std::ios::ate);
-  fsize = f.tellg();
-  f.seekg(0, std::ios::beg);
+  bytecode_if.open(argv[1], std::ios::binary | std::ios::ate);
+  bytecode_size = bytecode_if.tellg();
+  bytecode_if.seekg(0, std::ios::beg);
 
-  bytecode = new uint8_t[fsize];
-  f.read((char*)bytecode, fsize);
-
-  VM vm(bytecode, sizeof(bytecode));
+  bytecode = new uint8_t[bytecode_size];
+  bytecode_if.read((char*)bytecode, bytecode_size);
+  VM vm(bytecode, bytecode_size);
   vm.run();
   vm.status();
   return 0;
diff --git a/python/assembler.py b/python/assembler.py
index 59a92e0..1e474e4 100644
--- a/python/assembler.py
+++ b/python/assembler.py
@@ -36,22 +36,23 @@ assembled = bytearray()
 def to_uint8(data):
     alphanum = re.compile("^[0-9]+$")
     if isinstance(data, int):
-        return struct.pack("<b", data)
+        return struct.pack("<B", data)
     elif data.startswith("0x"):
-        return struct.pack("<b", int(data, 16))
+        return struct.pack("<B", int(data, 16))
     elif alphanum.match(data):  # only numbers
-        return struct.pack("<b", int(data))
+        return struct.pack("<B", int(data))
     else:
         return None
 
+
 def to_uint16(data):
     alphanum = re.compile("^[0-9]+$")
     if isinstance(data, int):
-        return struct.pack("<h", data)
+        return struct.pack("<H", data)
     elif data.startswith("0x"):
-        return struct.pack("<h", int(data, 16))
+        return struct.pack("<H", int(data, 16))
     elif alphanum.match(data):  # only numbers
-        return struct.pack("<h", int(data))
+        return struct.pack("<H", int(data))
     else:
         return None
 
@@ -62,6 +63,25 @@ def is_reg(data):
     return True
 
 
+def movi(op, dst, src):
+    global assembled
+    if (is_reg(dst)):
+        op_val = to_uint8(ops[op])
+        dst_val = to_uint8(regs[dst])
+        src_val = to_uint16(src)
+        if op_val and dst_val and src_val:
+            assembled += op_val + dst_val + src_val
+        else:
+            sys.stderr.write(
+                "ERROR WHILE ASSEMBLING UNKNOWN VALUES\n")
+            return False
+    else:
+        sys.stderr.write(
+            "ERROR WHILE ASSEMBLING UNKNOWN REGISTER: {}\n".format(dst))
+        return False
+    return True
+
+
 def assemble_code(line):
     global assembled
     sys.stdout.write("CODE: ")
@@ -74,16 +94,7 @@ def assemble_code(line):
         return False
     sys.stdout.write("{} {}\n".format(op_name, ", ".join(instruction[1::])))
     if op_name == "MOVI":
-        op = ops[op_name]
-        dst = instruction[1]
-        if (is_reg(dst)):
-            dst = to_uint8(regs[dst])
-            src = to_uint16(instruction[2])
-        else:
-            sys.stderr.write(
-                "ERROR WHILE ASSEMBLING UNKNOWN REGISTER: {}\n".format(dst))
-            return False
-        assembled += to_uint8(op) + dst + src
+        movi(op_name, instruction[1], instruction[2])
     return True
 
 
@@ -94,8 +105,13 @@ def assemble_data(line):
 
 def main():
     global assembled
-    with open("./test.gipu", 'r') as f:
+    if (len(sys.argv) < 2):
+        print("Usage: {} <file_to_assemble>".format(sys.argv[0]))
+        return
+
+    with open(sys.argv[1], 'r') as f:
         gen = (line.strip("\n") for line in f if line != "\n")
+        flag = None
 
         for line in gen:
             if line.startswith(tuple(section_names)):
@@ -105,6 +121,8 @@ def main():
                 assemble_data(line)
             elif flag == section_flags["CODE:"]:
                 assemble_code(line)
+        if not flag:
+            sys.stderr.write("Nothing was assembled! Did you use the section delimiters?\n")
     with open("./out.gipu", 'wb') as f:
         f.write(assembled)