diff --git a/src/radeon_crtc.c b/src/radeon_crtc.c
index c78ac43..a34849a 100644
--- a/src/radeon_crtc.c
+++ b/src/radeon_crtc.c
@@ -159,6 +159,7 @@ RADEONComputePLL(RADEONPLLPtr pll,
     freq = freq * 1000;
 
     ErrorF("freq: %lu\n", freq);
+    flags |= RADEON_PLL_USE_FRAC_FB_DIV;
 
     if (flags & RADEON_PLL_USE_REF_DIV)
 	min_ref_div = max_ref_div = pll->reference_div;
@@ -230,7 +231,8 @@ RADEONComputePLL(RADEONPLLPtr pll,
 		    tmp += (CARD64)pll->reference_freq * 1000 * frac_feedback_div;
 		    current_freq = RADEONDiv(tmp, ref_div * post_div);
 
-		    error = abs(current_freq - freq);
+		    error = freq - current_freq;
+		    error = error < 0 ? 0xFFFFFFFF : error;
 		    vco_diff = abs(vco - best_vco);
 
 		    if ((best_vco == 0 && error < best_error) ||