diff --git a/Makefile b/Makefile
index 9dc3d28a..cecb544b 100644
--- a/Makefile
+++ b/Makefile
@@ -194,11 +194,13 @@ build/src/libultra/2D300.o: OPTFLAGS := -O1 -g0
 build/src/libultra/io/controller.o: OPTFLAGS := -O1 -g0
 build/src/libultra/libc/string.o: OPTFLAGS := -O2 -g0
 build/src/libultra/libc/ldiv.o: OPTFLAGS := -O2 -g0
+build/src/libultra/gu/ortho.o: OPTFLAGS := -O3 -g0
 build/src/libultra/gu/lookat.o: OPTFLAGS := -O3 -g0
 
 # cc & asm-processor
 CC := $(ASM_PROC) $(ASM_PROC_FLAGS) $(IDO) -- $(AS) $(ASFLAGS) --
 build/src/libultra/gu/lookat.o: CC := $(IDO)
+build/src/libultra/gu/ortho.o: CC := $(IDO)
 #build/src/%.o: CC := $(ASM_PROC) $(ASM_PROC_FLAGS) $(IDO) -- $(AS) $(ASFLAGS) --
 
 all: uncompressed
diff --git a/src/libultra/gu/lookat.c b/src/libultra/gu/lookat.c
index a1829777..89ca18f3 100644
--- a/src/libultra/gu/lookat.c
+++ b/src/libultra/gu/lookat.c
@@ -1,9 +1,6 @@
 #include "global.h"
 #include "PR/gbi.h"
-
-void guMtxIdentF(float (*mf)[4]);
-
-float sqrtf(float value);
+#include "PR/gu.h"
 
 void guLookAtF(float mf[4][4], float xEye, float yEye, float zEye, float xAt, float yAt, float zAt, float xUp,
                float yUp, float zUp) {
diff --git a/src/libultra/gu/ortho.c b/src/libultra/gu/ortho.c
index a86fb619..14945f8c 100644
--- a/src/libultra/gu/ortho.c
+++ b/src/libultra/gu/ortho.c
@@ -1,5 +1,31 @@
-#include "common.h"
+#include "global.h"
+#include "PR/gu.h"
 
-#pragma GLOBAL_ASM("asm/us/nonmatchings/libultra/gu/ortho/guOrthoF.s")
+void guOrthoF(float mf[4][4], float l, float r, float b, float t, float n, float f, float scale) {
+    int i;
+    int j;
 
-#pragma GLOBAL_ASM("asm/us/nonmatchings/libultra/gu/ortho/guOrtho.s")
+    guMtxIdentF(mf);
+
+    mf[0][0] = 2 / (r - l);
+    mf[1][1] = 2 / (t - b);
+    mf[2][2] = -2 / (f - n);
+    mf[3][0] = -(r + l) / (r - l);
+    mf[3][1] = -(t + b) / (t - b);
+    mf[3][2] = -(f + n) / (f - n);
+    mf[3][3] = 1;
+
+    for (i = 0; i < 4; i++) {
+        for (j = 0; j < 4; j++) {
+            mf[i][j] *= scale;
+        }
+    }
+}
+
+void guOrtho(Mtx* m, float l, float r, float b, float t, float n, float f, float scale) {
+    Matrix mf;
+
+    guOrthoF(mf, l, r, b, t, n, f, scale);
+
+    guMtxF2L(mf, m);
+}