diff --git a/dlls/winex11.drv/mouse.c b/dlls/winex11.drv/mouse.c
index d4bfc5a1967..d78449c2cc7 100644
--- a/dlls/winex11.drv/mouse.c
+++ b/dlls/winex11.drv/mouse.c
@@ -74,8 +74,8 @@ static const UINT button_down_flags[NB_BUTTONS] =
     MOUSEEVENTF_RIGHTDOWN,
     MOUSEEVENTF_WHEEL,
     MOUSEEVENTF_WHEEL,
-    MOUSEEVENTF_XDOWN,  /* FIXME: horizontal wheel */
-    MOUSEEVENTF_XDOWN,
+    MOUSEEVENTF_HWHEEL,
+    MOUSEEVENTF_HWHEEL,
     MOUSEEVENTF_XDOWN,
     MOUSEEVENTF_XDOWN
 };
@@ -87,8 +87,8 @@ static const UINT button_up_flags[NB_BUTTONS] =
     MOUSEEVENTF_RIGHTUP,
     0,
     0,
-    MOUSEEVENTF_XUP,
-    MOUSEEVENTF_XUP,
+    0,
+    0,
     MOUSEEVENTF_XUP,
     MOUSEEVENTF_XUP
 };
@@ -100,8 +100,8 @@ static const UINT button_down_data[NB_BUTTONS] =
     0,
     WHEEL_DELTA,
     -WHEEL_DELTA,
-    XBUTTON1,
-    XBUTTON2,
+    -WHEEL_DELTA,
+    WHEEL_DELTA,
     XBUTTON1,
     XBUTTON2
 };
@@ -113,8 +113,8 @@ static const UINT button_up_data[NB_BUTTONS] =
     0,
     0,
     0,
-    XBUTTON1,
-    XBUTTON2,
+    0,
+    0,
     XBUTTON1,
     XBUTTON2
 };