diff --git a/hw/xfree86/drivers/modesetting/vblank.c b/hw/xfree86/drivers/modesetting/vblank.c
index c8da476b5..ea9e7a88c 100644
--- a/hw/xfree86/drivers/modesetting/vblank.c
+++ b/hw/xfree86/drivers/modesetting/vblank.c
@@ -120,7 +120,8 @@ static RRCrtcPtr
 rr_crtc_covering_box(ScreenPtr pScreen, BoxPtr box, Bool screen_is_xf86_hint)
 {
     rrScrPrivPtr pScrPriv;
-    RRCrtcPtr crtc, best_crtc;
+    RROutputPtr primary_output;
+    RRCrtcPtr crtc, best_crtc, primary_crtc;
     int coverage, best_coverage;
     int c;
     BoxRec crtc_box, cover_box;
@@ -136,6 +137,11 @@ rr_crtc_covering_box(ScreenPtr pScreen, BoxPtr box, Bool screen_is_xf86_hint)
     if (!pScrPriv)
         return NULL;
 
+    primary_crtc = NULL;
+    primary_output = RRFirstOutput(pScreen);
+    if (primary_output)
+        primary_crtc = primary_output->crtc;
+
     for (c = 0; c < pScrPriv->numCrtcs; c++) {
         crtc = pScrPriv->crtcs[c];
 
@@ -146,7 +152,8 @@ rr_crtc_covering_box(ScreenPtr pScreen, BoxPtr box, Bool screen_is_xf86_hint)
         rr_crtc_box(crtc, &crtc_box);
         box_intersect(&cover_box, &crtc_box, box);
         coverage = box_area(&cover_box);
-        if (coverage > best_coverage) {
+        if ((coverage > best_coverage) ||
+            (coverage == best_coverage && crtc == primary_crtc)) {
             best_crtc = crtc;
             best_coverage = coverage;
         }