diff --git a/src/sillymachine.adb b/src/sillymachine.adb
index 45a7242..5d9da1a 100644
--- a/src/sillymachine.adb
+++ b/src/sillymachine.adb
@@ -16,6 +16,23 @@ procedure sillymachine is
   Value : Byte;
 
 begin
+  
+  ValidHeader (0) := 6;
+  ValidHeader (1) := 148;
+  ValidHeader (2) := 32;
+  ValidHeader (3) := 118;
+  ValidHeader (4) := 101;
+  ValidHeader (5) := 114;
+  ValidHeader (6) := 121;
+  ValidHeader (7) := 95;
+  ValidHeader (8) := 115;
+  ValidHeader (9) := 105;
+  ValidHeader (10) := 108;
+  ValidHeader (11) := 108;
+  ValidHeader (12) := 121;
+  ValidHeader (13) := 0;
+  ValidHeader (14) := 0;
+  ValidHeader (15) := 0;
 
   if Argument_Count = 0 then
     New_Line(1);
@@ -27,15 +44,22 @@ begin
   FileNameLength := Argument (1)'Length;
   FileName(1 .. FileNameLength) := Argument (1);
 
-  --Bin_IO.Open(F, Bin_IO.In_File, FileName);
-  --while not Bin_IO.End_Of_File (F) loop
-  --  Bin_IO.Read(F, Value);
-  --  Arr (I) := Value;
-  --  I := I + 1;
-  --end loop;
-  --for i in 0 .. 15 loop
-  --  Put_Line(Byte'Image(Arr (i)));
-  --end loop;
+  Bin_IO.Open(F, Bin_IO.In_File, FileName);
+  while not Bin_IO.End_Of_File (F) loop
+    Bin_IO.Read(F, Value);
+    
+    if ValidHeader (I) = Value then
+      Value := Value; -- useless line so compiler does not complain
+    else
+      New_Line(1);
+      Put_Line("Error: Please use a valid sm binary file");
+      New_Line(1);
+      goto THE_END;
+    end if;
+    I := I + 1;
+
+  end loop;
+  Put_Line("Header passed");
 
 << THE_END >>
 end sillymachine;