diff --git a/Xi/exevents.c b/Xi/exevents.c
index a83d5edb3..bbe70e486 100644
--- a/Xi/exevents.c
+++ b/Xi/exevents.c
@@ -823,6 +823,7 @@ UpdateDeviceState(DeviceIntPtr device, xEvent* xE, int count)
 	if ((++xV)->type == DeviceValuator) {
 	    int *axisvals;
             int first = xV->first_valuator;
+            BOOL change = FALSE;
 
 	    if (xV->num_valuators &&
                 (!v || (xV->num_valuators &&
@@ -830,24 +831,91 @@ UpdateDeviceState(DeviceIntPtr device, xEvent* xE, int count)
 		FatalError("Bad valuators reported for device %s\n",
 			   device->name);
 	    if (v && v->axisVal) {
+                /* The device always stores values in absolute. Only the
+                 * delivery mode changes.
+                 * If device is mode Absolute, and event is Relative
+                 *     dev += event
+                 *     event = dev
+                 * If device is mode Absolute, and event is Absolute
+                 *     dev = event
+                 * If device is mode Relative, and event is Absolute
+                 *      swap = (event - device)
+                 *      dev = event
+                 *      event = delta
+                 * If device is mode Relative, and event is Relative
+                 *      dev += event
+                 *
+                 * XXX: axis clipping for relative events?
+                 */
 		axisvals = v->axisVal;
-		switch (xV->num_valuators) {
-		case 6:
-		    *(axisvals + first + 5) = xV->valuator5;
-		case 5:
-		    *(axisvals + first + 4) = xV->valuator4;
-		case 4:
-		    *(axisvals + first + 3) = xV->valuator3;
-		case 3:
-		    *(axisvals + first + 2) = xV->valuator2;
-		case 2:
-		    *(axisvals + first + 1) = xV->valuator1;
-		case 1:
-		    *(axisvals + first) = xV->valuator0;
-		case 0:
-		default:
-		    break;
-		}
+                if (xV->sequenceNumber & Absolute) {
+                    int delta;
+                    if (v->mode == Relative) /* device reports relative */
+                    {
+                        change = TRUE;
+                        xV->sequenceNumber &= ~Absolute;
+                    }
+
+                    switch (xV->num_valuators) {
+                        case 6:
+                            if (change) delta = xV->valuator5 - *(axisvals + first + 5);
+                            *(axisvals + first + 5) = xV->valuator5;
+                            if (change) xV->valuator5 = delta;
+                        case 5:
+                            if (change) delta = xV->valuator4 - *(axisvals + first + 4);
+                            *(axisvals + first + 4) = xV->valuator4;
+                            if (change) xV->valuator4 = delta;
+                        case 4:
+                            if (change) delta = xV->valuator3 - *(axisvals + first + 3);
+                            *(axisvals + first + 3) = xV->valuator3;
+                            if (change) xV->valuator3 = delta;
+                        case 3:
+                            if (change) delta = xV->valuator2 - *(axisvals + first + 2);
+                            *(axisvals + first + 2) = xV->valuator2;
+                            if (change) xV->valuator2 = delta;
+                        case 2:
+                            if (change) delta = xV->valuator1 - *(axisvals + first + 1);
+                            *(axisvals + first + 1) = xV->valuator1;
+                            if (change) xV->valuator1 = delta;
+                        case 1:
+                            if (change) delta = xV->valuator0 - *(axisvals + first);
+                            *(axisvals + first) = xV->valuator0;
+                            if (change) xV->valuator0 = delta;
+                        case 0:
+                        default:
+                            break;
+                    }
+		} else { /* event is relative */
+                    if (v->mode == Absolute) /* device reports absolute */
+                    {
+                        change = TRUE;
+                        xV->sequenceNumber |= Absolute;
+                    }
+
+                    switch (xV->num_valuators) {
+                        case 6:
+                            *(axisvals + first + 5) += xV->valuator5;
+                            if (change) xV->valuator5 = *(axisvals + first + 5);
+                        case 5:
+                            *(axisvals + first + 4) += xV->valuator4;
+                            if (change) xV->valuator4 = *(axisvals + first + 4);
+                        case 4:
+                            *(axisvals + first + 3) += xV->valuator3;
+                            if (change) xV->valuator3 = *(axisvals + first + 3);
+                        case 3:
+                            *(axisvals + first + 2) += xV->valuator2;
+                            if (change) xV->valuator2 = *(axisvals + first + 2);
+                        case 2:
+                            *(axisvals + first + 1) += xV->valuator1;
+                            if (change) xV->valuator1 = *(axisvals + first + 1);
+                        case 1:
+                            *(axisvals + first) += xV->valuator0;
+                            if (change) xV->valuator0 = *(axisvals + first);
+                        case 0:
+                        default:
+                            break;
+                    }
+                }
 	    }
 	}
     }
diff --git a/include/inputstr.h b/include/inputstr.h
index 8c1d5fc5a..d117e554d 100644
--- a/include/inputstr.h
+++ b/include/inputstr.h
@@ -174,7 +174,7 @@ typedef struct _ValuatorClassRec {
 
     AxisInfoPtr 	  axes;
     unsigned short	  numAxes;
-    int			  *axisVal;
+    int			  *axisVal; /* always absolute, but device-coord system */
     int                   dxremaind, dyremaind; /* for acceleration */
     CARD8	 	  mode;
 } ValuatorClassRec, *ValuatorClassPtr;