diff --git a/include/functions.h b/include/functions.h
index 347b42db..c77f4f1f 100644
--- a/include/functions.h
+++ b/include/functions.h
@@ -40,6 +40,9 @@ extern void HAL_Printf(s32 x, s32 y, char *str, ...);
 // C030.s
 extern s32 func_8000B4C4(void);
 
+// Yay0.s
+extern void Yay0_Decompress(void* src, void* dst);
+
 // D470.s
 extern void func_8000C8F8(void);
 extern void func_8000CEE4(s32, s32, void *, OSMesgQueue *);
diff --git a/splat.yaml b/splat.yaml
index 571c7bf6..08c95d55 100644
--- a/splat.yaml
+++ b/splat.yaml
@@ -53,7 +53,7 @@ segments:
     - [0xB230, c, gb_tower]
     - [0xC030, c] # extra sprites loader
     - [0xC3D0, asm, exception_set] # exception functions
-    - [0xC3F0, asm] # yay0 decoder
+    - [0xC3F0, hasm, yay0] # Yay0 decoder
     - [0xC4B0, bin, libleo_bootdisk]  # These are libleo's bootdisk and bootstrap files, but
     - [0xC910, bin, libleo_bootstrap] # have issues being disassembled, so are bins for now.
     - [0xC970, asm]
diff --git a/tools/symbol_addrs.txt b/tools/symbol_addrs.txt
index 51ed64cd..ea189cfd 100644
--- a/tools/symbol_addrs.txt
+++ b/tools/symbol_addrs.txt
@@ -562,4 +562,5 @@ draw_profiler = 0x80009F8C;
 HAL_Printf = 0x80008154;
 print_profiler_metrics = 0x8000A0FC;
 clear_profiler_data = 0x8000A21C;
-draw_profiler_bar_cpu_keep_max = 0x80009630;
\ No newline at end of file
+draw_profiler_bar_cpu_keep_max = 0x80009630;
+Yay0_Decompress = 0x8000B7F0;
\ No newline at end of file