diff -u -p ../../../../xorg-server-1.4.0.90.orig/hw/xfree86/common//xf86Helper.c ./xf86Helper.c
--- ../../../../xorg-server-1.4.0.90.orig/hw/xfree86/common//xf86Helper.c	2008-05-26 16:53:50.000000000 +0000
+++ hw/xfree86/common/xf86Helper.c	2008-05-26 17:09:52.000000000 +0000
@@ -1017,12 +1017,22 @@ 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;
@@ -1057,12 +1067,22 @@ 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;