diff --git a/src/lib.rs b/src/lib.rs
index 8d9f9c2..76448e5 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -129,6 +129,15 @@ pub mod sram;
 
 pub mod mgba;
 
+extern "C" {
+  /// This marks the end of the `.data` and `.bss` sections in IWRAM.
+  ///
+  /// Memory in IWRAM _before_ this location is not free to use, you'll trash
+  /// your globals and stuff. Memory here or after is freely available for use
+  /// (careful that you don't run into your own stack of course).
+  static __bss_end: u8;
+}
+
 newtype! {
   /// A color on the GBA is an RGB 5.5.5 within a `u16`
   #[derive(PartialOrd, Ord, Hash)]