Index: hw/xfree86/common/xf86Helper.c
===================================================================
--- hw/xfree86/common/xf86Helper.c.orig
+++ hw/xfree86/common/xf86Helper.c
@@ -997,12 +997,22 @@ xf86SetDpi(ScrnInfoPtr pScrn, int x, int
     } else if (pScrn->widthmm > 0 || pScrn->heightmm > 0) {
 	from = X_CONFIG;
 	if (pScrn->widthmm > 0) {
-	   pScrn->xDpi =
-		(int)((double)pScrn->virtualX * MMPERINCH / pScrn->widthmm);
+	   if (pScrn->modes && pScrn->modes->HDisplay > 0) {
+		pScrn->xDpi = 
+		    (int)((double) pScrn->modes->HDisplay * MMPERINCH / pScrn->widthmm);
+	   } else {
+		pScrn->xDpi =
+		    (int)((double)pScrn->virtualX * MMPERINCH / pScrn->widthmm);
+	   }
 	}
 	if (pScrn->heightmm > 0) {
-	   pScrn->yDpi =
-		(int)((double)pScrn->virtualY * MMPERINCH / pScrn->heightmm);
+	   if (pScrn->modes && pScrn->modes->VDisplay > 0) {
+		pScrn->yDpi =
+		    (int)((double)pScrn->modes->VDisplay * MMPERINCH / pScrn->heightmm);
+	   } else {
+		pScrn->yDpi =
+		    (int)((double)pScrn->virtualY * MMPERINCH / pScrn->heightmm);
+	   }
 	}
 	if (pScrn->xDpi > 0 && pScrn->yDpi <= 0)
 	    pScrn->yDpi = pScrn->xDpi;
@@ -1037,12 +1047,22 @@ xf86SetDpi(ScrnInfoPtr pScrn, int x, int
 	pScrn->widthmm = ddcWidthmm;
 	pScrn->heightmm = ddcHeightmm;
 	if (pScrn->widthmm > 0) {
-	   pScrn->xDpi =
-		(int)((double)pScrn->virtualX * MMPERINCH / pScrn->widthmm);
+	    if (pScrn->modes && pScrn->modes->HDisplay > 0) {
+		pScrn->xDpi =
+                   (int)((double) pScrn->modes->HDisplay * MMPERINCH / pScrn->widthmm);
+	    } else {
+		pScrn->xDpi =
+		   (int)((double)pScrn->virtualX * MMPERINCH / pScrn->widthmm);
+	    }
 	}
 	if (pScrn->heightmm > 0) {
-	   pScrn->yDpi =
-		(int)((double)pScrn->virtualY * MMPERINCH / pScrn->heightmm);
+	   if (pScrn->modes && pScrn->modes->VDisplay > 0) {
+		pScrn->yDpi =
+		   (int)((double)pScrn->modes->VDisplay * MMPERINCH / pScrn->heightmm);
+	   } else {
+		pScrn->yDpi =
+		   (int)((double)pScrn->virtualY * MMPERINCH / pScrn->heightmm);
+	   }
 	}
 	if (pScrn->xDpi > 0 && pScrn->yDpi <= 0)
 	    pScrn->yDpi = pScrn->xDpi;