diff --git a/clutter/cogl/gles/cogl.c b/clutter/cogl/gles/cogl.c
index 422d8b6..16cf666 100644
--- a/clutter/cogl/gles/cogl.c
+++ b/clutter/cogl/gles/cogl.c
@@ -37,6 +37,7 @@
 #include "cogl-context.h"
 
 #include "cogl-gles2-wrapper.h"
+#include <math.h>
 
 /* GL error to string conversion */
 #if COGL_DEBUG
@@ -365,9 +366,8 @@ set_clip_plane (GLint plane_num,
 
   /* Calculate the angle between the axes and the line crossing the
      two points */
-  angle = (atan2f (vertex_b[1] - vertex_a[1] *
-                                            vertex_b[0] - vertex_a[0]),
-		          COGL_RADIANS_TO_DEGREES);
+  angle = atan2f (vertex_b[1] - vertex_a[1],
+                  vertex_b[0] - vertex_a[0]) * (180.0/G_PI);
 
   GE( cogl_wrap_glPushMatrix () );
   /* Load the identity matrix and multiply by the reverse of the
@@ -558,15 +558,13 @@ cogl_perspective (float fovy,
    * 2) When working with small numbers, we can are loosing significant
    * precision
    */
-  ymax = (zNear *
-                         (sinf (fovy_rad_half) /
-                                         cosf (fovy_rad_half)));
+  ymax = (zNear * (sinf (fovy_rad_half) / cosf (fovy_rad_half)));
   xmax = (ymax * aspect);
 
   x = (zNear / xmax);
   y = (zNear / ymax);
   c = (-(zFar + zNear) / ( zFar - zNear));
-  d = (-((2 * zFar * zNear)) / (zFar - zNear));
+  d = (-(2 * zFar) * zNear) / (zFar - zNear);
 
 #define M(row,col)  m[col*4+row]
   M(0,0) = x;
@@ -671,13 +669,13 @@ cogl_setup_viewport (guint        w,
   if (fovy != 60.0)
     {
       float fovy_rad = (fovy * G_PI) / 180;
-  
-      z_camera = (sinf (fovy_rad) /
-                                 cosf (fovy_rad)) >> 1;
+
+      z_camera = (sinf (fovy_rad) / cosf (fovy_rad)) / 2;
     }
   
 
-  GE( cogl_wrap_glTranslatex (-1 << 15, -1 << 15, -z_camera) );
+
+  GE( cogl_wrap_glTranslatex (-0.5f, -0.5f, -z_camera) );
 
   GE( cogl_wrap_glScalex ( 1.0 / width,
                           -1.0 / height,