diff --git a/dlls/winedos/int33.c b/dlls/winedos/int33.c
index 7f0a868cc2a..fc2c6bef5ad 100644
--- a/dlls/winedos/int33.c
+++ b/dlls/winedos/int33.c
@@ -35,13 +35,37 @@ WINE_DEFAULT_DEBUG_CHANNEL(int);
 
 static struct
 {
-  DWORD x, y, but;
-  WORD lbcount, rbcount, rlastx, rlasty, llastx, llasty;
-  FARPROC16 callback;
-  WORD callmask;
-  WORD VMPratio, HMPratio, oldx, oldy;
+    WORD x, y, but;
+    WORD lbcount, rbcount, rlastx, rlasty, llastx, llasty;
+    FARPROC16 callback;
+    WORD callmask;
+    WORD VMPratio, HMPratio, oldx, oldy;
 } mouse_info;
 
+
+/**********************************************************************
+ *          INT33_ResetMouse
+ *
+ * Handler for:
+ * - subfunction 0x00 (reset mouse)
+ * - subfunction 0x21 (software reset)
+ */
+static void INT33_ResetMouse( CONTEXT86 *context )
+{
+    memset( &mouse_info, 0, sizeof(mouse_info) );
+    
+    /* Set the default mickey/pixel ratio */
+    mouse_info.HMPratio = 8;
+    mouse_info.VMPratio = 16;
+
+    if (context)
+    {
+        SET_AX( context, 0xFFFF ); /* driver installed */
+        SET_BX( context, 3 );      /* number of buttons */
+    }
+}
+
+
 /**********************************************************************
  *	    DOSVM_Int33Handler (WINEDOS16.151)
  *
@@ -49,86 +73,112 @@ static struct
  */
 void WINAPI DOSVM_Int33Handler( CONTEXT86 *context )
 {
-  switch (LOWORD(context->Eax)) {
-  case 0x00:
-  case 0x21:
-    TRACE("Reset mouse driver and request status\n");
-    SET_AX( context, 0xFFFF ); /* installed */
-    SET_BX( context, 3 );      /* # of buttons */
-    memset( &mouse_info, 0, sizeof(mouse_info) );
-    /* Set the default mickey/pixel ratio */
-    mouse_info.HMPratio = 8;
-    mouse_info.VMPratio = 16;
-    break;
-  case 0x01:
-    FIXME("Show mouse cursor\n");
-    break;
-  case 0x02:
-    FIXME("Hide mouse cursor\n");
-    break;
-  case 0x03:
-    TRACE("Return mouse position and button status: (%ld,%ld) and %ld\n",
-         mouse_info.x, mouse_info.y, mouse_info.but);
-    SET_BX( context, mouse_info.but );
-    SET_CX( context, mouse_info.x );
-    SET_DX( context, mouse_info.y );
-    break;
-  case 0x04:
-    FIXME("Position mouse cursor\n");
-    break;
-  case 0x05:
-    TRACE("Return Mouse button press Information for %s mouse button\n",
-          BX_reg(context) ? "right" : "left");
-    if (BX_reg(context)) {
-      SET_BX( context, mouse_info.rbcount );
-      mouse_info.rbcount = 0;
-      SET_CX( context, mouse_info.rlastx );
-      SET_DX( context, mouse_info.rlasty );
-    } else {
-      SET_BX( context, mouse_info.lbcount );
-      mouse_info.lbcount = 0;
-      SET_CX( context, mouse_info.llastx );
-      SET_DX( context, mouse_info.llasty );
+    switch (AX_reg(context))
+    {
+    case 0x0000:
+        TRACE("Reset mouse driver and request status\n");
+        INT33_ResetMouse( context );
+        break;
+
+    case 0x0001:
+        FIXME("Show mouse cursor\n");
+        break;
+
+    case 0x0002:
+        FIXME("Hide mouse cursor\n");
+        break;
+
+    case 0x0003:
+        TRACE("Return mouse position and button status: (%d,%d) and %d\n",
+              mouse_info.x, mouse_info.y, mouse_info.but);
+        SET_BX( context, mouse_info.but );
+        SET_CX( context, mouse_info.x );
+        SET_DX( context, mouse_info.y );
+        break;
+
+    case 0x0004:
+        FIXME("Position mouse cursor\n");
+        break;
+
+    case 0x0005:
+        TRACE("Return Mouse button press Information for %s mouse button\n",
+              BX_reg(context) ? "right" : "left");
+        if (BX_reg(context)) 
+        {
+            SET_BX( context, mouse_info.rbcount );
+            mouse_info.rbcount = 0;
+            SET_CX( context, mouse_info.rlastx );
+            SET_DX( context, mouse_info.rlasty );
+        } 
+        else 
+        {
+            SET_BX( context, mouse_info.lbcount );
+            mouse_info.lbcount = 0;
+            SET_CX( context, mouse_info.llastx );
+            SET_DX( context, mouse_info.llasty );
+        }
+        SET_AX( context, mouse_info.but );
+        break;
+
+    case 0x0007:
+        FIXME("Define horizontal mouse cursor range %d..%d\n",
+              CX_reg(context), DX_reg(context));
+        break;
+
+    case 0x0008:
+        FIXME("Define vertical mouse cursor range %d..%d\n",
+              CX_reg(context), DX_reg(context));
+        break;
+
+    case 0x0009:
+        FIXME("Define graphics mouse cursor\n");
+        break;
+
+    case 0x000A:
+        FIXME("Define text mouse cursor\n");
+        break;
+
+    case 0x000B:
+        TRACE("Read Mouse motion counters\n");
+        {
+            int dx = ((int)mouse_info.x - (int)mouse_info.oldx)
+                * (mouse_info.HMPratio / 8);
+            int dy = ((int)mouse_info.y - (int)mouse_info.oldy)
+                * (mouse_info.VMPratio / 8);
+
+            SET_CX( context, (WORD)dx );
+            SET_DX( context, (WORD)dy );
+
+            mouse_info.oldx = mouse_info.x;
+            mouse_info.oldy = mouse_info.y;
+        }
+        break;
+
+    case 0x000C:
+        TRACE("Define mouse interrupt subroutine\n");
+        mouse_info.callmask = CX_reg(context);
+        mouse_info.callback = (FARPROC16)MAKESEGPTR(context->SegEs, 
+                                                    DX_reg(context));
+        break;
+
+    case 0x000F:
+        TRACE("Set mickey/pixel ratio\n");
+        mouse_info.HMPratio = CX_reg(context);
+        mouse_info.VMPratio = DX_reg(context);
+        break;
+
+    case 0x0010:
+        FIXME("Define screen region for update\n");
+        break;
+
+    case 0x0021:
+        TRACE("Software reset\n");
+        INT33_ResetMouse( context );
+        break;
+
+    default:
+        INT_BARF(context,0x33);
     }
-    SET_AX( context, mouse_info.but );
-    break;
-  case 0x07:
-    FIXME("Define horizontal mouse cursor range %d..%d\n",
-          CX_reg(context), DX_reg(context));
-    break;
-  case 0x08:
-    FIXME("Define vertical mouse cursor range %d..%d\n",
-          CX_reg(context), DX_reg(context));
-    break;
-  case 0x09:
-    FIXME("Define graphics mouse cursor\n");
-    break;
-  case 0x0A:
-    FIXME("Define text mouse cursor\n");
-    break;
-  case 0x0B:
-    TRACE("Read Mouse motion counters\n");
-    SET_CX( context, (mouse_info.x - mouse_info.oldx) * (mouse_info.HMPratio / 8) );
-    SET_DX( context, (mouse_info.y - mouse_info.oldy) * (mouse_info.VMPratio / 8) );
-    mouse_info.oldx = mouse_info.x;
-    mouse_info.oldy = mouse_info.y;
-    break;
-  case 0x0C:
-    TRACE("Define mouse interrupt subroutine\n");
-    mouse_info.callmask = CX_reg(context);
-    mouse_info.callback = (FARPROC16)MAKESEGPTR(context->SegEs, LOWORD(context->Edx));
-    break;
-  case 0x0F:
-    TRACE("Set mickey/pixel ratio\n");
-    mouse_info.HMPratio = CX_reg(context);
-    mouse_info.VMPratio = DX_reg(context);
-    break;
-  case 0x10:
-    FIXME("Define screen region for update\n");
-    break;
-  default:
-    INT_BARF(context,0x33);
-  }
 }
 
 typedef struct {