diff --git a/Xext/vidmode.c b/Xext/vidmode.c
index 06ac3c49c..00cdc4239 100644
--- a/Xext/vidmode.c
+++ b/Xext/vidmode.c
@@ -460,12 +460,16 @@ ProcVidModeAddModeLine(ClientPtr client)
         len =
             client->req_len -
             bytes_to_int32(sizeof(xXF86OldVidModeAddModeLineReq));
+        if (len != oldstuff->privsize)
+            return BadLength;
     }
     else {
         REQUEST_AT_LEAST_SIZE(xXF86VidModeAddModeLineReq);
         len =
             client->req_len -
             bytes_to_int32(sizeof(xXF86VidModeAddModeLineReq));
+        if (len != stuff->privsize)
+            return BadLength;
     }
 
     if (ver < 2) {
@@ -515,9 +519,6 @@ ProcVidModeAddModeLine(ClientPtr client)
            stuff->after_vsyncend, stuff->after_vtotal,
            (unsigned long) stuff->after_flags);
 
-    if (len != stuff->privsize)
-        return BadLength;
-
     if (stuff->screen >= screenInfo.numScreens)
         return BadValue;
     pScreen = screenInfo.screens[stuff->screen];
@@ -634,12 +635,28 @@ ProcVidModeDeleteModeLine(ClientPtr client)
         len =
             client->req_len -
             bytes_to_int32(sizeof(xXF86OldVidModeDeleteModeLineReq));
+        if (len != oldstuff->privsize) {
+            DebugF("req_len = %ld, sizeof(Req) = %d, privsize = %ld, "
+                   "len = %d, length = %d\n",
+                   (unsigned long) client->req_len,
+                   (int) sizeof(xXF86VidModeDeleteModeLineReq) >> 2,
+                   (unsigned long) stuff->privsize, len, client->req_len);
+            return BadLength;
+        }
     }
     else {
         REQUEST_AT_LEAST_SIZE(xXF86VidModeDeleteModeLineReq);
         len =
             client->req_len -
             bytes_to_int32(sizeof(xXF86VidModeDeleteModeLineReq));
+        if (len != stuff->privsize) {
+            DebugF("req_len = %ld, sizeof(Req) = %d, privsize = %ld, "
+                   "len = %d, length = %d\n",
+                   (unsigned long) client->req_len,
+                   (int) sizeof(xXF86VidModeDeleteModeLineReq) >> 2,
+                   (unsigned long) stuff->privsize, len, client->req_len);
+            return BadLength;
+        }
     }
 
     if (ver < 2) {
@@ -669,15 +686,6 @@ ProcVidModeDeleteModeLine(ClientPtr client)
            stuff->vdisplay, stuff->vsyncstart, stuff->vsyncend, stuff->vtotal,
            (unsigned long) stuff->flags);
 
-    if (len != stuff->privsize) {
-        DebugF("req_len = %ld, sizeof(Req) = %d, privsize = %ld, "
-               "len = %d, length = %d\n",
-               (unsigned long) client->req_len,
-               (int) sizeof(xXF86VidModeDeleteModeLineReq) >> 2,
-               (unsigned long) stuff->privsize, len, client->req_len);
-        return BadLength;
-    }
-
     if (stuff->screen >= screenInfo.numScreens)
         return BadValue;
     pScreen = screenInfo.screens[stuff->screen];
@@ -762,12 +770,16 @@ ProcVidModeModModeLine(ClientPtr client)
         len =
             client->req_len -
             bytes_to_int32(sizeof(xXF86OldVidModeModModeLineReq));
+        if (len != oldstuff->privsize)
+            return BadLength;
     }
     else {
         REQUEST_AT_LEAST_SIZE(xXF86VidModeModModeLineReq);
         len =
             client->req_len -
             bytes_to_int32(sizeof(xXF86VidModeModModeLineReq));
+        if (len != stuff->privsize)
+            return BadLength;
     }
 
     if (ver < 2) {
@@ -794,9 +806,6 @@ ProcVidModeModModeLine(ClientPtr client)
            stuff->vdisplay, stuff->vsyncstart, stuff->vsyncend,
            stuff->vtotal, (unsigned long) stuff->flags);
 
-    if (len != stuff->privsize)
-        return BadLength;
-
     if (stuff->hsyncstart < stuff->hdisplay ||
         stuff->hsyncend < stuff->hsyncstart ||
         stuff->htotal < stuff->hsyncend ||
@@ -899,12 +908,16 @@ ProcVidModeValidateModeLine(ClientPtr client)
         REQUEST_AT_LEAST_SIZE(xXF86OldVidModeValidateModeLineReq);
         len = client->req_len -
             bytes_to_int32(sizeof(xXF86OldVidModeValidateModeLineReq));
+        if (len != oldstuff->privsize)
+            return BadLength;
     }
     else {
         REQUEST_AT_LEAST_SIZE(xXF86VidModeValidateModeLineReq);
         len =
             client->req_len -
             bytes_to_int32(sizeof(xXF86VidModeValidateModeLineReq));
+        if (len != stuff->privsize)
+            return BadLength;
     }
 
     if (ver < 2) {
@@ -1063,12 +1076,16 @@ ProcVidModeSwitchToMode(ClientPtr client)
         len =
             client->req_len -
             bytes_to_int32(sizeof(xXF86OldVidModeSwitchToModeReq));
+        if (len != stuff->privsize)
+            return BadLength;
     }
     else {
         REQUEST_AT_LEAST_SIZE(xXF86VidModeSwitchToModeReq);
         len =
             client->req_len -
             bytes_to_int32(sizeof(xXF86VidModeSwitchToModeReq));
+        if (len != stuff->privsize)
+            return BadLength;
     }
 
     if (ver < 2) {
@@ -1099,9 +1116,6 @@ ProcVidModeSwitchToMode(ClientPtr client)
            stuff->vdisplay, stuff->vsyncstart, stuff->vsyncend, stuff->vtotal,
            (unsigned long) stuff->flags);
 
-    if (len != stuff->privsize)
-        return BadLength;
-
     if (stuff->screen >= screenInfo.numScreens)
         return BadValue;
     pScreen = screenInfo.screens[stuff->screen];