diff -ru xf86-input-evdev-2.9.1/src/evdev.c xf86-input-evdev-2.9.1.new/src/evdev.c
--- xf86-input-evdev-2.9.1/src/evdev.c  2014-11-26 00:33:56.000000000 +0100
+++ xf86-input-evdev-2.9.1.new/src/evdev.c      2015-01-22 15:34:48.313671266 +0100
@@ -751,6 +751,14 @@
 
     if (ev->code == ABS_MT_SLOT) {
         EvdevProcessTouch(pInfo);
+        if (ev->value >= num_slots(pEvdev) ) {
+            LogMessageVerbSigSafe(X_WARNING, 0,
+                                  "%s: Slot index %d out of bounds (max %d), touch events may be incorrect.\n",
+                                  pInfo->name,
+                                  ev->value,
+                                  num_slots(pEvdev)-1);
+            return;
+        }
         pEvdev->cur_slot = ev->value;
     } else
     {