diff --git a/src/legacy_crtc.c b/src/legacy_crtc.c
index 489fecf..937d269 100644
--- a/src/legacy_crtc.c
+++ b/src/legacy_crtc.c
@@ -1708,7 +1708,7 @@ legacy_crtc_mode_set(xf86CrtcPtr crtc, DisplayModePtr mode,
     RADEONInfoPtr info = RADEONPTR(pScrn);
     int i = 0;
     double dot_clock = 0;
-    int pll_flags = RADEON_PLL_LEGACY;
+    int pll_flags = RADEON_PLL_LEGACY | RADEON_PLL_USE_REF_DIV;
     Bool update_tv_routing = FALSE;
     Bool tilingChanged = FALSE;