diff --git a/Makefile b/Makefile
index 7a80f5ad89..1ec16e5bf6 100644
--- a/Makefile
+++ b/Makefile
@@ -66,60 +66,109 @@ ifeq ($(VERSION),ntsc-1.0)
   REGION ?= JP
   PLATFORM := N64
   DEBUG_FEATURES ?= 0
+  BUILD_DATE := 98-10-21
+  BUILD_TIME := 04:56:31
+  REVISION := 0
 else ifeq ($(VERSION),ntsc-1.1)
   REGIONAL_CHECKSUM := 1
   REGION ?= JP
   PLATFORM := N64
   DEBUG_FEATURES ?= 0
+  BUILD_DATE := 98-10-26
+  BUILD_TIME := 10:58:45
+  REVISION := 1
 else ifeq ($(VERSION),pal-1.0)
   REGION ?= EU
   PLATFORM := N64
   DEBUG_FEATURES ?= 0
+  BUILD_DATE := 98-11-10
+  BUILD_TIME := 14:34:22
+  REVISION := 0
 else ifeq ($(VERSION),ntsc-1.2)
   REGIONAL_CHECKSUM := 1
   REGION ?= JP
   PLATFORM := N64
   DEBUG_FEATURES ?= 0
+  BUILD_DATE := 98-11-12
+  BUILD_TIME := 18:17:03
+  REVISION := 2
 else ifeq ($(VERSION),pal-1.1)
   REGION ?= EU
   PLATFORM := N64
   DEBUG_FEATURES ?= 0
+  BUILD_DATE := 98-11-18
+  BUILD_TIME := 17:36:49
+  REVISION := 1
 else ifeq ($(VERSION),gc-jp)
   REGION ?= JP
   PLATFORM := GC
   DEBUG_FEATURES ?= 0
+  BUILD_DATE := 02-10-29
+  BUILD_TIME := 23:49:53
+  REVISION := 15
 else ifeq ($(VERSION),gc-jp-mq)
   REGION ?= JP
   PLATFORM := GC
   DEBUG_FEATURES ?= 0
+  BUILD_DATE := 02-10-30
+  BUILD_TIME := 00:15:15
+  REVISION := 15
 else ifeq ($(VERSION),gc-us)
   REGION ?= US
   PLATFORM := GC
   DEBUG_FEATURES ?= 0
+  BUILD_DATE := 02-12-19
+  BUILD_TIME := 13:28:09
+  REVISION := 15
 else ifeq ($(VERSION),gc-us-mq)
   REGION ?= US
   PLATFORM := GC
   DEBUG_FEATURES ?= 0
+  BUILD_DATE := 02-12-19
+  BUILD_TIME := 14:05:42
+  REVISION := 15
 else ifeq ($(VERSION),gc-eu-mq-dbg)
   REGION ?= EU
   PLATFORM := GC
   DEBUG_FEATURES ?= 1
+  BUILD_DATE := 03-02-21
+  BUILD_TIME := 00:16:31
+  REVISION := 15
 else ifeq ($(VERSION),gc-eu)
   REGION ?= EU
   PLATFORM := GC
   DEBUG_FEATURES ?= 0
+  BUILD_DATE := 03-02-21
+  BUILD_TIME := 20:12:23
+  REVISION := 15
 else ifeq ($(VERSION),gc-eu-mq)
   REGION ?= EU
   PLATFORM := GC
   DEBUG_FEATURES ?= 0
+  BUILD_DATE := 03-02-21
+  BUILD_TIME := 20:37:19
+  REVISION := 15
 else ifeq ($(VERSION),gc-jp-ce)
   REGION ?= JP
   PLATFORM := GC
   DEBUG_FEATURES ?= 0
+  BUILD_DATE := 03-10-08
+  BUILD_TIME := 21:53:00
+  REVISION := 15
 else
 $(error Unsupported version $(VERSION))
 endif
 
+ifeq ($(PLATFORM),N64)
+  BUILD_CREATOR := zelda@srd44
+  LIBULTRA_VERSION := I
+  LIBULTRA_PATCH := 1
+else
+  BUILD_CREATOR := zelda@srd022j
+  LIBULTRA_VERSION := L
+  LIBULTRA_PATCH := 0
+endif
+
 # ORIG_COMPILER cannot be combined with a non-IDO compiler. Check for this case and error out if found.
 ifneq ($(COMPILER),ido)
   ifeq ($(ORIG_COMPILER),1)
@@ -149,8 +198,11 @@ CPPFLAGS += -P -xc -fno-dollars-in-identifiers
 
 # Converts e.g. ntsc-1.0 to NTSC_1_0
 VERSION_MACRO := $(shell echo $(VERSION) | tr a-z-. A-Z__)
-CPP_DEFINES += -DOOT_VERSION=$(VERSION_MACRO)
+CPP_DEFINES += -DOOT_VERSION=$(VERSION_MACRO) -DOOT_REVISION=$(REVISION)
 CPP_DEFINES += -DOOT_REGION=REGION_$(REGION)
+CPP_DEFINES += -DBUILD_CREATOR="\"$(BUILD_CREATOR)\"" -DBUILD_DATE="\"$(BUILD_DATE)\"" -DBUILD_TIME="\"$(BUILD_TIME)\""
+CPP_DEFINES += -DLIBULTRA_VERSION=LIBULTRA_VERSION_$(LIBULTRA_VERSION)
+CPP_DEFINES += -DLIBULTRA_PATCH=$(LIBULTRA_PATCH)
 
 ifeq ($(PLATFORM),N64)
   CPP_DEFINES += -DPLATFORM_N64=1 -DPLATFORM_GC=0
@@ -494,7 +546,7 @@ $(BUILD_DIR)/src/libultra/libc/ll.o: MIPS_VERSION := -mips3 -32
 $(BUILD_DIR)/src/libultra/libc/llcvt.o: OPTFLAGS := -O1
 $(BUILD_DIR)/src/libultra/libc/llcvt.o: MIPS_VERSION := -mips3 -32
 
-ifeq ($(PLATFORM),N64)
+ifeq ($(LIBULTRA_VERSION),I)
 $(BUILD_DIR)/src/libultra/gu/%.o: OPTFLAGS := -O3
 $(BUILD_DIR)/src/libultra/io/%.o: OPTFLAGS := -O1
 $(BUILD_DIR)/src/libultra/libc/%.o: OPTFLAGS := -O3
diff --git a/format.py b/format.py
index 775d188c18..a5faa79c97 100755
--- a/format.py
+++ b/format.py
@@ -31,7 +31,7 @@ APPLY_OPTS = "--format --style=file"
 # Compiler options used with Clang-Tidy
 # Normal warnings are disabled with -Wno-everything to focus only on tidying
 INCLUDES = "-Iinclude -Isrc -Ibuild/gc-eu-mq-dbg -I."
-DEFINES = "-D_LANGUAGE_C -DNON_MATCHING -DF3DEX_GBI_2"
+DEFINES = "-D_LANGUAGE_C -DNON_MATCHING -DF3DEX_GBI_2 -DBUILD_CREATOR=\"\" -DBUILD_DATE=__DATE__ -DBUILD_TIME=__TIME__"
 COMPILER_OPTS = f"-fno-builtin -std=gnu90 -m32 -Wno-everything {INCLUDES} {DEFINES}"
 
 
diff --git a/include/ultra64.h b/include/ultra64.h
index e1f9a7c9b9..e8a4bd0ca7 100644
--- a/include/ultra64.h
+++ b/include/ultra64.h
@@ -31,6 +31,7 @@
 #include "ultra64/motor.h"
 #include "ultra64/R4300.h"
 #include "ultra64/ucode.h"
+#include "ultra64/version.h"
 
 union uObjBg;
 
@@ -42,7 +43,7 @@ void osStopThread(OSThread* thread);
 void osViExtendVStart(u32 value);
 s32 osRecvMesg(OSMesgQueue* mq, OSMesg* msg, s32 flag);
 
-#if PLATFORM_N64
+#if LIBULTRA_VERSION < LIBULTRA_VERSION_K
 void osInitialize(void);
 #else
 #define osInitialize()               \
diff --git a/include/ultra64/version.h b/include/ultra64/version.h
new file mode 100644
index 0000000000..00d772845e
--- /dev/null
+++ b/include/ultra64/version.h
@@ -0,0 +1,14 @@
+#ifndef ULTRA64_VERSION_H
+#define ULTRA64_VERSION_H
+
+#define LIBULTRA_VERSION_D  'D'
+#define LIBULTRA_VERSION_E  'E'
+#define LIBULTRA_VERSION_F  'F'
+#define LIBULTRA_VERSION_G  'G'
+#define LIBULTRA_VERSION_H  'H'
+#define LIBULTRA_VERSION_I  'I'
+#define LIBULTRA_VERSION_J  'J'
+#define LIBULTRA_VERSION_K  'K'
+#define LIBULTRA_VERSION_L  'L'
+
+#endif
diff --git a/src/boot/build.c b/src/boot/build.c
index 49992adc54..31e48096b2 100644
--- a/src/boot/build.c
+++ b/src/boot/build.c
@@ -1,39 +1,5 @@
 #include "versions.h"
 
-#if PLATFORM_N64
-const char gBuildCreator[] = "zelda@srd44";
-#else
-const char gBuildCreator[] = "zelda@srd022j";
-#endif
-
-#if OOT_VERSION == NTSC_1_0
-const char gBuildDate[] = "98-10-21 04:56:31";
-#elif OOT_VERSION == NTSC_1_1
-const char gBuildDate[] = "98-10-26 10:58:45";
-#elif OOT_VERSION == PAL_1_0
-const char gBuildDate[] = "98-11-10 14:34:22";
-#elif OOT_VERSION == NTSC_1_2
-const char gBuildDate[] = "98-11-12 18:17:03";
-#elif OOT_VERSION == PAL_1_1
-const char gBuildDate[] = "98-11-18 17:36:49";
-#elif OOT_VERSION == GC_JP
-const char gBuildDate[] = "02-10-29 23:49:53";
-#elif OOT_VERSION == GC_JP_MQ
-const char gBuildDate[] = "02-10-30 00:15:15";
-#elif OOT_VERSION == GC_US
-const char gBuildDate[] = "02-12-19 13:28:09";
-#elif OOT_VERSION == GC_US_MQ
-const char gBuildDate[] = "02-12-19 14:05:42";
-#elif OOT_VERSION == GC_EU_MQ_DBG
-const char gBuildDate[] = "03-02-21 00:16:31";
-#elif OOT_VERSION == GC_EU
-const char gBuildDate[] = "03-02-21 20:12:23";
-#elif OOT_VERSION == GC_EU_MQ
-const char gBuildDate[] = "03-02-21 20:37:19";
-#elif OOT_VERSION == GC_JP_CE
-const char gBuildDate[] = "03-10-08 21:53:00";
-#else
-#error "Unsupported OOT_VERSION"
-#endif
-
+const char gBuildCreator[] = BUILD_CREATOR;
+const char gBuildDate[] = BUILD_DATE " " BUILD_TIME;
 const char gBuildMakeOption[] = "";
diff --git a/src/libultra/gu/rotate.c b/src/libultra/gu/rotate.c
index b9108e1bc5..7d495e98ef 100644
--- a/src/libultra/gu/rotate.c
+++ b/src/libultra/gu/rotate.c
@@ -8,7 +8,7 @@ void guRotateF(f32 m[4][4], f32 a, f32 x, f32 y, f32 z) {
     f32 bc;
     f32 ca;
     f32 t;
-#if !PLATFORM_N64
+#if LIBULTRA_VERSION >= LIBULTRA_VERSION_K
     f32 xs;
     f32 ys;
     f32 zs;
@@ -27,14 +27,14 @@ void guRotateF(f32 m[4][4], f32 a, f32 x, f32 y, f32 z) {
 
     guMtxIdentF(m);
 
-#if PLATFORM_N64
-#define xs (x * sine)
-#define ys (y * sine)
-#define zs (z * sine)
-#else
+#if LIBULTRA_VERSION >= LIBULTRA_VERSION_K
     xs = x * sine;
     ys = y * sine;
     zs = z * sine;
+#else
+#define xs (x * sine)
+#define ys (y * sine)
+#define zs (z * sine)
 #endif
 
     t = x * x;
diff --git a/src/libultra/os/exceptasm.s b/src/libultra/os/exceptasm.s
index 6b8003fd28..3c55d66ac8 100644
--- a/src/libultra/os/exceptasm.s
+++ b/src/libultra/os/exceptasm.s
@@ -4,6 +4,7 @@
 #include "ultra64/message.h"
 #include "ultra64/thread.h"
 #include "ultra64/exception.h"
+#include "ultra64/version.h"
 
 .set noat
 .set noreorder
@@ -448,7 +449,7 @@ pi:
     andi    $t1, $s1, MI_INTR_PI
     beqz    $t1, dp
      nop
-#if PLATFORM_N64
+#if LIBULTRA_VERSION < LIBULTRA_VERSION_J
     // Clear interrupt and mask out pi interrupt
     li      $t1, PI_STATUS_CLR_INTR
     lui     $at, %hi(PHYS_TO_K1(PI_STATUS_REG))
@@ -855,7 +856,7 @@ LEAF(__osPopThread)
      sw     $t9, ($a0)
 END(__osPopThread)
 
-#if !PLATFORM_N64
+#if LIBULTRA_VERSION >= LIBULTRA_VERSION_K
 LEAF(__osNop)
     jr      $ra
      nop
diff --git a/src/libultra/os/initialize.c b/src/libultra/os/initialize.c
index e985d551d9..427a517710 100644
--- a/src/libultra/os/initialize.c
+++ b/src/libultra/os/initialize.c
@@ -16,12 +16,14 @@ OSHWIntr __OSGlobalIntMask = OS_IM_ALL;
 
 u32 __osFinalrom;
 
-#if PLATFORM_N64
+#if LIBULTRA_VERSION < LIBULTRA_VERSION_K
 
 #define OSINITIALIZE_FUNC osInitialize
 #define SPEED_PARAM_FUNC createSpeedParam
 
+#if (LIBULTRA_VERSION == LIBULTRA_VERSION_I && LIBULTRA_PATCH == 1) || (LIBULTRA_VERSION == LIBULTRA_VERSION_J)
 static void SPEED_PARAM_FUNC(void);
+#endif
 
 #else
 
@@ -46,14 +48,14 @@ void SPEED_PARAM_FUNC(void) {
 
 void OSINITIALIZE_FUNC(void) {
     u32 pifdata;
-#if PLATFORM_N64
+#if LIBULTRA_VERSION < LIBULTRA_VERSION_K
     u32 clock = 0;
 #endif
 
     __osFinalrom = true;
     __osSetSR(__osGetSR() | SR_CU1);
     __osSetFpcCsr(FPCSR_FS | FPCSR_EV);
-#if !PLATFORM_N64
+#if LIBULTRA_VERSION >= LIBULTRA_VERSION_K
     __osSetWatchLo(0x04900000);
 #endif
 
@@ -71,9 +73,11 @@ void OSINITIALIZE_FUNC(void) {
 
     osWritebackDCache((void*)K0BASE, E_VEC - K0BASE + sizeof(__osExceptionVector));
     osInvalICache((void*)K0BASE, E_VEC - K0BASE + sizeof(__osExceptionVector));
+#if (LIBULTRA_VERSION == LIBULTRA_VERSION_I && LIBULTRA_PATCH == 1) || (LIBULTRA_VERSION > LIBULTRA_VERSION_I)
     SPEED_PARAM_FUNC();
     osUnmapTLBAll();
     osMapTLBRdb();
+#endif
 
     osClockRate = osClockRate * 3 / 4;
 
@@ -89,19 +93,21 @@ void OSINITIALIZE_FUNC(void) {
         osViClock = VI_NTSC_CLOCK;
     }
 
+#if (LIBULTRA_VERSION == LIBULTRA_VERSION_I && LIBULTRA_PATCH == 1) || (LIBULTRA_VERSION >= LIBULTRA_VERSION_J)
     // If PreNMI is pending, loop until reset
     if (__osGetCause() & CAUSE_IP5) {
         while (true) {
             ;
         }
     }
+#endif
 
     IO_WRITE(AI_CONTROL_REG, AI_CONTROL_DMA_ON);
     IO_WRITE(AI_DACRATE_REG, AI_MAX_DAC_RATE - 1);
     IO_WRITE(AI_BITRATE_REG, AI_MAX_BIT_RATE - 1);
 }
 
-#if PLATFORM_N64
+#if (LIBULTRA_VERSION == LIBULTRA_VERSION_I && LIBULTRA_PATCH == 1) || (LIBULTRA_VERSION == LIBULTRA_VERSION_J)
 static void SPEED_PARAM_FUNC(void) {
     __Dom1SpeedParam.type = DEVICE_TYPE_INIT;
     __Dom1SpeedParam.latency = IO_READ(PI_BSD_DOM1_LAT_REG);
diff --git a/src/libultra/os/settimer.c b/src/libultra/os/settimer.c
index 194f4eff78..a876641e88 100644
--- a/src/libultra/os/settimer.c
+++ b/src/libultra/os/settimer.c
@@ -2,7 +2,7 @@
 
 s32 osSetTimer(OSTimer* timer, OSTime countdown, OSTime interval, OSMesgQueue* mq, OSMesg msg) {
     UNUSED OSTime time;
-#if !PLATFORM_N64
+#if LIBULTRA_VERSION >= LIBULTRA_VERSION_K
     OSTimer* next;
     u32 count;
     u32 value;
@@ -21,12 +21,7 @@ s32 osSetTimer(OSTimer* timer, OSTime countdown, OSTime interval, OSMesgQueue* m
     timer->mq = mq;
     timer->msg = msg;
 
-#if PLATFORM_N64
-    time = __osInsertTimer(timer);
-    if (__osTimerList->next == timer) {
-        __osSetTimerIntr(time);
-    }
-#else
+#if LIBULTRA_VERSION >= LIBULTRA_VERSION_K
     prevInt = __osDisableInt();
     if (__osTimerList->next != __osTimerList) {
         if (1) {}
@@ -46,6 +41,11 @@ s32 osSetTimer(OSTimer* timer, OSTime countdown, OSTime interval, OSMesgQueue* m
     __osSetTimerIntr(__osTimerList->next->value);
 
     __osRestoreInt(prevInt);
+#else
+    time = __osInsertTimer(timer);
+    if (__osTimerList->next == timer) {
+        __osSetTimerIntr(time);
+    }
 #endif
 
     return 0;
diff --git a/src/libultra/os/timerintr.c b/src/libultra/os/timerintr.c
index 943aca0ffc..ce5c12fc5f 100644
--- a/src/libultra/os/timerintr.c
+++ b/src/libultra/os/timerintr.c
@@ -63,7 +63,7 @@ void __osSetTimerIntr(OSTime time) {
     OSTime newTime;
     u32 prevInt;
 
-#if !PLATFORM_N64
+#if LIBULTRA_VERSION >= LIBULTRA_VERSION_K
     if (time < 468) {
         time = 468;
     }
diff --git a/src/makerom/rom_header.h b/src/makerom/rom_header.h
index 1069ae86fe..65cfc89da3 100644
--- a/src/makerom/rom_header.h
+++ b/src/makerom/rom_header.h
@@ -54,13 +54,13 @@
  * and what libultra version (os_ver) it uses.
  *
  * The hardware revision for a retail N64 is (2,0).
- * The libultra version may be a single letter, without quotes.
+ * The libultra version must be a single char, in quotes.
  */
-#define LIBULTRA_VERSION(hw_major, hw_minor, os_ver)   \
+#define OS_VERSION(hw_major, hw_minor, os_ver)         \
     .half 0;                                           \
     .byte (hw_major) * 10 + (hw_minor);                \
     _os_ver_start = .;                                 \
-    .ascii #os_ver ;                                   \
+    .byte (os_ver) ;                                   \
     .if (. - _os_ver_start) != 1;                      \
         .error "OS version should be just one letter"; \
     .endif
diff --git a/src/makerom/rom_header.s b/src/makerom/rom_header.s
index 525bee6e88..d3d938cda3 100644
--- a/src/makerom/rom_header.s
+++ b/src/makerom/rom_header.s
@@ -1,4 +1,5 @@
 #include "rom_header.h"
+#include "ultra64/version.h"
 #include "region.h"
 #include "versions.h"
 
@@ -6,11 +7,7 @@
 /* 0x01 */ PI_DOMAIN_1_CFG(64, 18, 7, 3)
 /* 0x04 */ SYSTEM_CLOCK_RATE_SETTING(0xF)
 /* 0x08 */ ENTRYPOINT(0x80000400)
-#if PLATFORM_N64
-/* 0x0C */ LIBULTRA_VERSION(2, 0, I)
-#else
-/* 0x0C */ LIBULTRA_VERSION(2, 0, L)
-#endif
+/* 0x0C */ OS_VERSION(2, 0, LIBULTRA_VERSION)
 /* 0x10 */ CHECKSUM()
 /* 0x18 */ PADDING(8)
 /* 0x20 */ ROM_NAME("THE LEGEND OF ZELDA")
@@ -28,12 +25,4 @@
 #elif OOT_REGION == REGION_EU
 /* 0x3E */ REGION(PAL)
 #endif
-#if OOT_VERSION == NTSC_1_0 || OOT_VERSION == PAL_1_0
-/* 0x3F */ GAME_REVISION(0)
-#elif OOT_VERSION == NTSC_1_1 || OOT_VERSION == PAL_1_1
-/* 0x3F */ GAME_REVISION(1)
-#elif OOT_VERSION == NTSC_1_2
-/* 0x3F */ GAME_REVISION(2)
-#else
-/* 0x3F */ GAME_REVISION(15)
-#endif
+/* 0x3F */ GAME_REVISION(OOT_REVISION)