diff --git a/glslUtil/Makefile b/glslUtil/Makefile
new file mode 100644
index 0000000..c5213ff
--- /dev/null
+++ b/glslUtil/Makefile
@@ -0,0 +1,10 @@
+export SCONSFLAGS := -Q
+
+all:
+	@scons
+
+install:
+	@scons $@
+
+clean:
+	@scons -c
diff --git a/glslUtil/SConstruct b/glslUtil/SConstruct
new file mode 100644
index 0000000..cef95c3
--- /dev/null
+++ b/glslUtil/SConstruct
@@ -0,0 +1,4 @@
+# vim:filetype=python
+
+env = Environment()
+env.Object('glslUtil.o', 'glslUtil.c')
diff --git a/glslUtil/glslUtil.c b/glslUtil/glslUtil.c
index c1ab190..959b93a 100644
--- a/glslUtil/glslUtil.c
+++ b/glslUtil/glslUtil.c
@@ -1,38 +1,48 @@
 
+#include <string.h>
 #include "glslUtil.h"
 
 void guMatrixLoadIdentity(guMatrix4x4 *m)
 {
-    for (int i = 0; i < 4; i++)
+    int i, j;
+    for (i = 0; i < 4; i++)
     {
-        for (int j = 0; j < 4; j++)
+        for (j = 0; j < 4; j++)
         {
-            m[i][j] = (i == j) ? 1.0 : 0.0;
+            (*m)[i][j] = (i == j) ? 1.0 : 0.0;
         }
     }
 }
 
 void guMatrixMult(guMatrix4x4 *m, guMatrix4x4 *a, guMatrix4x4 *b)
 {
-    for (int i = 0; i < 4; i++)
+    guMatrix4x4 tmp;
+    int i, j, p;
+    if (m == a)
     {
-        for (int j = 0; j < 4; j++)
+        memcpy(&tmp, a, sizeof(tmp));
+        a = &tmp;
+    }
+    for (i = 0; i < 4; i++)
+    {
+        for (j = 0; j < 4; j++)
         {
             float v = 0.0;
-            for (int p = 0; p < 4; p++)
+            for (p = 0; p < 4; p++)
             {
-                v += a[i][p] * b[p][j];
+                v += (*a)[i][p] * (*b)[p][j];
             }
-            m[i][j] = v;
+            (*m)[i][j] = v;
         }
     }
 }
 
 void guMatrixTranslate(guMatrix4x4 *m, float x, float y, float z)
 {
-    for (int i = 0; i < 4; i++)
+    int i;
+    for (i = 0; i < 4; i++)
     {
-        m[i][3] += m[i][0] * x + m[i][1] * y + m[i][2] * z;
+        (*m)[i][3] += (*m)[i][0] * x + (*m)[i][1] * y + (*m)[i][2] * z;
     }
 }
 
@@ -41,10 +51,11 @@ void guMatrixFrustum(guMatrix4x4 *m,
         float bottom, float top,
         float near, float far)
 {
+    int i, j;
     guMatrix4x4 mult;
-    for (int i = 0; i < 4; i++)
+    for (i = 0; i < 4; i++)
     {
-        for (int j = 0; j < 4; j++)
+        for (j = 0; j < 4; j++)
         {
             mult[i][j] = 0.0;
         }
@@ -56,5 +67,5 @@ void guMatrixFrustum(guMatrix4x4 *m,
     mult[2][2] = - (far + near) / (far - near);
     mult[2][3] = - 2 * far * near / (far - near);
     mult[3][2] = -1.0;
-    guMatrixMult(m, &mult);
+    guMatrixMult(m, m, &mult);
 }