diff --git a/src/mesa/tnl/t_vb_arbprogram.c b/src/mesa/tnl/t_vb_arbprogram.c
index 70e1048f140..4288bd3bef9 100644
--- a/src/mesa/tnl/t_vb_arbprogram.c
+++ b/src/mesa/tnl/t_vb_arbprogram.c
@@ -105,7 +105,7 @@ static GLfloat RoughApproxPow2(GLfloat t)
    fi.i = (fi.i << 23) + 0x3f800000;
    return fi.f;
 #else
-   return (GLfloat) _mesa_pow(2.0, floor_t0);
+   return (GLfloat) _mesa_pow(2.0, t);
 #endif
 }