diff --git a/Makefile b/Makefile
index 11848c626..fcf396696 100644
--- a/Makefile
+++ b/Makefile
@@ -76,6 +76,7 @@ $(B_DIR)/lib/ultra/io/visetevent.o: OPT_LVL := -O1
 $(B_DIR)/lib/ultra/os/destroythread.o: OPT_LVL := -O1
 $(B_DIR)/lib/ultra/os/resetglobalintmask.o: OPT_LVL := -O1
 $(B_DIR)/lib/ultra/os/setthreadpri.o: OPT_LVL := -O1
+$(B_DIR)/lib/ultra/os/startthread.o: OPT_LVL := -O1
 $(B_DIR)/lib/ultra/os/stopthread.o: OPT_LVL := -O1
 $(B_DIR)/lib/ultra/os/thread.o: OPT_LVL := -O1
 $(B_DIR)/lib/ultra/os/yieldthread.o: OPT_LVL := -O1
diff --git a/src/lib/ultra/os/startthread.c b/src/lib/ultra/os/startthread.c
index c780b35bb..37827ef0d 100644
--- a/src/lib/ultra/os/startthread.c
+++ b/src/lib/ultra/os/startthread.c
@@ -1,95 +1,33 @@
 #include <libultra_internal.h>
+#include "game/data/data_000000.h"
 
-GLOBAL_ASM(
-glabel osStartThread
-/*    481f0:	27bdffd8 */ 	addiu	$sp,$sp,-40
-/*    481f4:	afbf001c */ 	sw	$ra,0x1c($sp)
-/*    481f8:	afa40028 */ 	sw	$a0,0x28($sp)
-/*    481fc:	afb10018 */ 	sw	$s1,0x18($sp)
-/*    48200:	0c01256c */ 	jal	__osDisableInt
-/*    48204:	afb00014 */ 	sw	$s0,0x14($sp)
-/*    48208:	8fae0028 */ 	lw	$t6,0x28($sp)
-/*    4820c:	24010001 */ 	addiu	$at,$zero,0x1
-/*    48210:	00408025 */ 	or	$s0,$v0,$zero
-/*    48214:	95d10010 */ 	lhu	$s1,0x10($t6)
-/*    48218:	1221000c */ 	beq	$s1,$at,.L0004824c
-/*    4821c:	24010008 */ 	addiu	$at,$zero,0x8
-/*    48220:	1621002a */ 	bne	$s1,$at,.L000482cc
-/*    48224:	00000000 */ 	nop
-/*    48228:	8fb80028 */ 	lw	$t8,0x28($sp)
-/*    4822c:	240f0002 */ 	addiu	$t7,$zero,0x2
-/*    48230:	3c048006 */ 	lui	$a0,%hi(__osRunQueue)
-/*    48234:	a70f0010 */ 	sh	$t7,0x10($t8)
-/*    48238:	8fa50028 */ 	lw	$a1,0x28($sp)
-/*    4823c:	0c000f2e */ 	jal	__osEnqueueThread
-/*    48240:	24840938 */ 	addiu	$a0,$a0,%lo(__osRunQueue)
-/*    48244:	10000021 */ 	b	.L000482cc
-/*    48248:	00000000 */ 	nop
-.L0004824c:
-/*    4824c:	8fb90028 */ 	lw	$t9,0x28($sp)
-/*    48250:	8f280008 */ 	lw	$t0,0x8($t9)
-/*    48254:	11000005 */ 	beqz	$t0,.L0004826c
-/*    48258:	00000000 */ 	nop
-/*    4825c:	3c098006 */ 	lui	$t1,%hi(__osRunQueue)
-/*    48260:	25290938 */ 	addiu	$t1,$t1,%lo(__osRunQueue)
-/*    48264:	1509000a */ 	bne	$t0,$t1,.L00048290
-/*    48268:	00000000 */ 	nop
-.L0004826c:
-/*    4826c:	8fab0028 */ 	lw	$t3,0x28($sp)
-/*    48270:	240a0002 */ 	addiu	$t2,$zero,0x2
-/*    48274:	3c048006 */ 	lui	$a0,%hi(__osRunQueue)
-/*    48278:	a56a0010 */ 	sh	$t2,0x10($t3)
-/*    4827c:	8fa50028 */ 	lw	$a1,0x28($sp)
-/*    48280:	0c000f2e */ 	jal	__osEnqueueThread
-/*    48284:	24840938 */ 	addiu	$a0,$a0,%lo(__osRunQueue)
-/*    48288:	10000010 */ 	b	.L000482cc
-/*    4828c:	00000000 */ 	nop
-.L00048290:
-/*    48290:	8fad0028 */ 	lw	$t5,0x28($sp)
-/*    48294:	240c0008 */ 	addiu	$t4,$zero,0x8
-/*    48298:	a5ac0010 */ 	sh	$t4,0x10($t5)
-/*    4829c:	8fae0028 */ 	lw	$t6,0x28($sp)
-/*    482a0:	8dc40008 */ 	lw	$a0,0x8($t6)
-/*    482a4:	0c000f2e */ 	jal	__osEnqueueThread
-/*    482a8:	01c02825 */ 	or	$a1,$t6,$zero
-/*    482ac:	8faf0028 */ 	lw	$t7,0x28($sp)
-/*    482b0:	0c000f40 */ 	jal	__osPopThread
-/*    482b4:	8de40008 */ 	lw	$a0,0x8($t7)
-/*    482b8:	00408825 */ 	or	$s1,$v0,$zero
-/*    482bc:	3c048006 */ 	lui	$a0,%hi(__osRunQueue)
-/*    482c0:	24840938 */ 	addiu	$a0,$a0,%lo(__osRunQueue)
-/*    482c4:	0c000f2e */ 	jal	__osEnqueueThread
-/*    482c8:	02202825 */ 	or	$a1,$s1,$zero
-.L000482cc:
-/*    482cc:	3c188006 */ 	lui	$t8,%hi(__osRunningThread)
-/*    482d0:	8f180940 */ 	lw	$t8,%lo(__osRunningThread)($t8)
-/*    482d4:	17000005 */ 	bnez	$t8,.L000482ec
-/*    482d8:	00000000 */ 	nop
-/*    482dc:	0c000f44 */ 	jal	__osDispatchThread
-/*    482e0:	00000000 */ 	nop
-/*    482e4:	1000000f */ 	b	.L00048324
-/*    482e8:	00000000 */ 	nop
-.L000482ec:
-/*    482ec:	3c198006 */ 	lui	$t9,%hi(__osRunningThread)
-/*    482f0:	3c098006 */ 	lui	$t1,%hi(__osRunQueue)
-/*    482f4:	8d290938 */ 	lw	$t1,%lo(__osRunQueue)($t1)
-/*    482f8:	8f390940 */ 	lw	$t9,%lo(__osRunningThread)($t9)
-/*    482fc:	8d2a0004 */ 	lw	$t2,0x4($t1)
-/*    48300:	8f280004 */ 	lw	$t0,0x4($t9)
-/*    48304:	010a082a */ 	slt	$at,$t0,$t2
-/*    48308:	10200006 */ 	beqz	$at,.L00048324
-/*    4830c:	00000000 */ 	nop
-/*    48310:	240b0002 */ 	addiu	$t3,$zero,0x2
-/*    48314:	3c048006 */ 	lui	$a0,%hi(__osRunQueue)
-/*    48318:	a72b0010 */ 	sh	$t3,0x10($t9)
-/*    4831c:	0c000ee8 */ 	jal	__osEnqueueAndYield
-/*    48320:	24840938 */ 	addiu	$a0,$a0,%lo(__osRunQueue)
-.L00048324:
-/*    48324:	0c012588 */ 	jal	__osRestoreInt
-/*    48328:	02002025 */ 	or	$a0,$s0,$zero
-/*    4832c:	8fbf001c */ 	lw	$ra,0x1c($sp)
-/*    48330:	8fb00014 */ 	lw	$s0,0x14($sp)
-/*    48334:	8fb10018 */ 	lw	$s1,0x18($sp)
-/*    48338:	03e00008 */ 	jr	$ra
-/*    4833c:	27bd0028 */ 	addiu	$sp,$sp,0x28
-);
+void osStartThread(OSThread *t)
+{
+	register u32 saveMask = __osDisableInt();
+
+	switch (t->state) {
+	case OS_STATE_WAITING:
+		t->state = OS_STATE_RUNNABLE;
+		__osEnqueueThread(&__osRunQueue, t);
+		break;
+	case OS_STATE_STOPPED:
+		if (t->queue == NULL || t->queue == &__osRunQueue) {
+			t->state = OS_STATE_RUNNABLE;
+			__osEnqueueThread(&__osRunQueue, t);
+		} else {
+			t->state = OS_STATE_WAITING;
+			__osEnqueueThread(t->queue, t);
+			__osEnqueueThread(&__osRunQueue, __osPopThread(t->queue));
+		}
+		break;
+	}
+
+	if (__osRunningThread == NULL) {
+		__osDispatchThread();
+	} else if (__osRunningThread->priority < __osRunQueue->priority) {
+		__osRunningThread->state = OS_STATE_RUNNABLE;
+		__osEnqueueAndYield(&__osRunQueue);
+	}
+
+	__osRestoreInt(saveMask);
+}