diff --git a/src/memory.ml b/src/memory.ml
index fab5630..f6a5943 100644
--- a/src/memory.ml
+++ b/src/memory.ml
@@ -8,6 +8,8 @@ type map = {
   rom_bank_00 : bytes; (* cartridge, 16KB *)
   rom_bank_01 : bytes; (* additional bank, 16KB *)
   vram : bytes; (* Video RAM, 8KB *)
+  wram_bank_0 : bytes; (* work RAM, 4KB *)
+  wram_bank_1 : bytes; (* work RAM, 4KB *)
   io : bytes; (* I/O ports *)
   hram : bytes; (* High RAM, 8KB *)
   interrupt : bytes; (* Interrupt Enable Register *)
@@ -18,6 +20,8 @@ let init (cartridge: Cartridge.t) =
     rom_bank_00 = sub cartridge.full_rom 0 0x4000;
     rom_bank_01 = create 0x4000;
     vram = create 0x2000;
+    wram_bank_0 = create 0x1000;
+    wram_bank_1 = create 0x1000;
     io = create 0x0080;
     hram = create 0x2000;
     interrupt = create 1
@@ -28,6 +32,9 @@ let get_mem_bank mem addr =
   | x when x < 0x4000 -> mem.rom_bank_00, x
   | x when x < 0x8000 -> mem.rom_bank_01, (x - 0x4000)
   | x when x < 0xA000 -> mem.vram,  (x - 0x8000)
+  | x when x < 0xC000 -> failwith "Unimplemented memory range."
+  | x when x < 0xD000 -> mem.wram_bank_0,  (x - 0xC000)
+  | x when x < 0xE000 -> mem.wram_bank_1,  (x - 0xD000)
   | x when x < 0xFF00 -> failwith "Unimplemented memory range."
   | x when x < 0xFF80 -> mem.io, x - 0xFF00
   | x when x < 0xFFFF -> mem.hram, x - 0xFF80