diff --git a/doc/Concepts.md b/doc/Concepts.md
index 0d21433..f6633f1 100644
--- a/doc/Concepts.md
+++ b/doc/Concepts.md
@@ -57,7 +57,7 @@ Also peripherals can be made accessible via the network. More on that later.
 var back = Peripheral.getRedstone("back");
 back.setOutput(true);
 
-var drive Peripheral.getDrive("drive_0");
+var drive = Peripheral.getDrive("drive_0");
 drive.eject();
 ```
 
@@ -114,7 +114,7 @@ The idea is that you can register all you disposable resources in the handle and
 A process can be used as a command on the terminal or as a service. See [bin/HelloWorld.hx](../src/bin/HelloWorld.hx) for an example.
 Basically everything that runs and is not part of the kernel is a process.
 
-In order for you program to be used it needs to be registered in the `BinStore` and the `DCEHack` manually. 
+~~In order for you program to be used it needs to be registered in the `BinStore` and the `DCEHack` manually. ~~
 
 # EndOfLoop
 
@@ -208,3 +208,19 @@ rpc.addNumber(3,7).handle((p)->{
     }
 });
 ```
+
+# Build system and flags
+
+We use `make` to build the project. If you want a prod build just run `make` and if you want the debug build run `make debug`.
+The `build` directory should contain all needed files. 
+
+- `bundle.min.lua`: The minified final file
+- `bundle.polyfill.lua`: The same as above just not minified. use this when debugging.
+- `haxe.lua`: Intermediate file. Polyfill not yet added.
+- `haxe.zip`: The compressed `bundle.min.lua`. 
+- `unpack.*`: Same as the bundle files. Used to unpack and run the `haxe.zip` file.
+
+The follwing haxe flags can be used in the code or can be set in the makefile.
+
+- `debug`: Is set when debug
+- `kv_use_native`: If set use the native CC serialize and unserialize functions instead of the Haxe ones. See [KVStore.hx](../src/lib/KVStore.hx) for more.