diff --git a/src/mesa/drivers/dri/i915tex/i915_fragprog.c b/src/mesa/drivers/dri/i915tex/i915_fragprog.c
index a4b22a0..feed41e 100644
--- a/src/mesa/drivers/dri/i915tex/i915_fragprog.c
+++ b/src/mesa/drivers/dri/i915tex/i915_fragprog.c
@@ -316,11 +316,29 @@ upload_program(struct i915_fragment_program *p)
       case OPCODE_COS:
          src0 = src_vector(p, &inst->SrcReg[0], program);
          tmp = i915_get_utemp(p);
+	
+	// perform range reduction 
+	i915_emit_arith(p, 
+			A0_MAD, 
+			tmp, A0_DEST_CHANNEL_X, 0,
+			src0, i915_emit_const1f(p, 0.159154943), 
+			i915_emit_const1f(p, 0.5));
+
+	i915_emit_arith(p, 
+			A0_FRC, 
+			tmp, A0_DEST_CHANNEL_X, 0, 
+			tmp, 0, 0); 
+
+	i915_emit_arith(p, 
+			A0_MAD,
+			tmp, A0_DEST_CHANNEL_X, 0,
+			tmp, i915_emit_const1f(p, 6.283185307), 
+			i915_emit_const1f(p, -3.141592654));
 
          i915_emit_arith(p,
                          A0_MUL,
                          tmp, A0_DEST_CHANNEL_X, 0,
-                         src0, i915_emit_const1f(p, 1.0 / (M_PI * 2)), 0);
+                         tmp, i915_emit_const1f(p, 1.0 / (M_PI * 2)), 0);
 
          i915_emit_arith(p, A0_MOD, tmp, A0_DEST_CHANNEL_X, 0, tmp, 0, 0);
 
@@ -639,10 +657,28 @@ upload_program(struct i915_fragment_program *p)
          src0 = src_vector(p, &inst->SrcReg[0], program);
          tmp = i915_get_utemp(p);
 
+	// perform range reduction 
+	i915_emit_arith(p, 
+			A0_MAD, 
+			tmp, A0_DEST_CHANNEL_X, 0,
+			src0, i915_emit_const1f(p, 0.159154943), 
+			i915_emit_const1f(p, 0.5));
+
+	i915_emit_arith(p, 
+			A0_FRC, 
+			tmp, A0_DEST_CHANNEL_X, 0, 
+			tmp, 0, 0); 
+
+	i915_emit_arith(p, 
+			A0_MAD,
+			tmp, A0_DEST_CHANNEL_X, 0,
+			tmp, i915_emit_const1f(p, 6.283185307), 
+			i915_emit_const1f(p, -3.141592654));
+
          i915_emit_arith(p,
                          A0_MUL,
                          tmp, A0_DEST_CHANNEL_X, 0,
-                         src0, i915_emit_const1f(p, 1.0 / (M_PI * 2)), 0);
+                         tmp, i915_emit_const1f(p, 1.0 / (M_PI * 2)), 0);
 
          i915_emit_arith(p, A0_MOD, tmp, A0_DEST_CHANNEL_X, 0, tmp, 0, 0);