diff --git a/Makefile b/Makefile
index 5500c2dbb..a35eddd98 100644
--- a/Makefile
+++ b/Makefile
@@ -68,6 +68,7 @@ $(B_DIR)/lib/ultra/gu/ortho.o: LOOPUNROLL :=
 $(B_DIR)/lib/ultra/libc/ll.o: MIPSISET := -mips3 -o32
 $(B_DIR)/lib/ultra/libc/llcvt.o: MIPSISET := -mips3 -o32
 
+$(B_DIR)/lib/ultra/gu/frustum.o: OPT_LVL := -O3
 $(B_DIR)/lib/ultra/gu/ortho.o: OPT_LVL := -O3
 $(B_DIR)/lib/ultra/gu/scale.o: OPT_LVL := -O3
 $(B_DIR)/lib/ultra/io/ai.o: OPT_LVL := -O1
diff --git a/src/lib/ultra/gu/frustum.c b/src/lib/ultra/gu/frustum.c
index dc9634495..1492d5c2e 100644
--- a/src/lib/ultra/gu/frustum.c
+++ b/src/lib/ultra/gu/frustum.c
@@ -22,44 +22,11 @@ void guFrustumF(float mf[4][4], float l, float r, float b, float t, float n, flo
 	}
 }
 
-GLOBAL_ASM(
-glabel guFrustum
-/*    4ff80:	27bdff98 */ 	addiu	$sp,$sp,-104
-/*    4ff84:	44856000 */ 	mtc1	$a1,$f12
-/*    4ff88:	44867000 */ 	mtc1	$a2,$f14
-/*    4ff8c:	44878000 */ 	mtc1	$a3,$f16
-/*    4ff90:	c7a40078 */ 	lwc1	$f4,0x78($sp)
-/*    4ff94:	c7a6007c */ 	lwc1	$f6,0x7c($sp)
-/*    4ff98:	c7a80080 */ 	lwc1	$f8,0x80($sp)
-/*    4ff9c:	c7aa0084 */ 	lwc1	$f10,0x84($sp)
-/*    4ffa0:	afbf0024 */ 	sw	$ra,0x24($sp)
-/*    4ffa4:	afa40068 */ 	sw	$a0,0x68($sp)
-/*    4ffa8:	44056000 */ 	mfc1	$a1,$f12
-/*    4ffac:	44067000 */ 	mfc1	$a2,$f14
-/*    4ffb0:	44078000 */ 	mfc1	$a3,$f16
-/*    4ffb4:	27a40028 */ 	addiu	$a0,$sp,0x28
-/*    4ffb8:	e7a40010 */ 	swc1	$f4,0x10($sp)
-/*    4ffbc:	e7a60014 */ 	swc1	$f6,0x14($sp)
-/*    4ffc0:	e7a80018 */ 	swc1	$f8,0x18($sp)
-/*    4ffc4:	0c013f88 */ 	jal	guFrustumF
-/*    4ffc8:	e7aa001c */ 	swc1	$f10,0x1c($sp)
-/*    4ffcc:	27a40028 */ 	addiu	$a0,$sp,0x28
-/*    4ffd0:	0c0128d8 */ 	jal	guMtxF2L
-/*    4ffd4:	8fa50068 */ 	lw	$a1,0x68($sp)
-/*    4ffd8:	8fbf0024 */ 	lw	$ra,0x24($sp)
-/*    4ffdc:	27bd0068 */ 	addiu	$sp,$sp,0x68
-/*    4ffe0:	03e00008 */ 	jr	$ra
-/*    4ffe4:	00000000 */ 	nop
-/*    4ffe8:	00000000 */ 	nop
-/*    4ffec:	00000000 */ 	nop
-);
+void guFrustum(Mtx *m, float l, float r, float b, float t, float n, float f, float scale)
+{
+	float mf[4][4];
 
-// Mismatch: Goal moves a3 to f16, while this stores it in the stack.
-//void guFrustum(Mtx *m, float l, float r, float b, float t, float n, float f, float scale)
-//{
-//	float mf[4][4];
-//
-//	guFrustumF(mf, l, r, b, t, n, f, scale);
-//
-//	guMtxF2L(mf, m);
-//}
+	guFrustumF(mf, l, r, b, t, n, f, scale);
+
+	guMtxF2L(mf, m);
+}