diff --git a/src/hardware/r_opengl/r_opengl.c b/src/hardware/r_opengl/r_opengl.c
index 3a8be6a0..af3f3cb6 100644
--- a/src/hardware/r_opengl/r_opengl.c
+++ b/src/hardware/r_opengl/r_opengl.c
@@ -2056,7 +2056,7 @@ EXPORT void HWRAPI(DrawMD2) (INT32 *gl_cmd_buffer, md2_frame_t *frame, FTransfor
 EXPORT void HWRAPI(SetTransform) (FTransform *stransform)
 {
 	static boolean special_splitscreen;
-	float used_fov;
+	GLdouble used_fov;
 	pglLoadIdentity();
 	if (stransform)
 	{
@@ -2088,7 +2088,7 @@ EXPORT void HWRAPI(SetTransform) (FTransform *stransform)
 	pglLoadIdentity();
 	if (special_splitscreen)
 	{
-		used_fov = atan(tan(used_fov*M_PI/360)*0.8)*360/M_PI;
+		used_fov = atan(tan(used_fov*M_PIl/360)*0.8)*360/M_PIl;
 		GLPerspective(used_fov, 2*ASPECT_RATIO);
 	}
 	else