diff --git a/client/displayservers/Wayland/input.c b/client/displayservers/Wayland/input.c
index 45fc672e..4e9c5595 100644
--- a/client/displayservers/Wayland/input.c
+++ b/client/displayservers/Wayland/input.c
@@ -149,29 +149,37 @@ static void pointerAxisHandler(void * data, struct wl_pointer * pointer,
   app_handleWheelMotion(delta / WL_SCROLL_STEP);
 }
 
-static int mapWaylandToSpiceButton(uint32_t button)
+static int mapWaylandButton(uint32_t button)
 {
   switch (button)
   {
     case BTN_LEFT:
-      return 1;  // SPICE_MOUSE_BUTTON_LEFT
+      return 1;
     case BTN_MIDDLE:
-      return 2;  // SPICE_MOUSE_BUTTON_MIDDLE
+      return 2;
     case BTN_RIGHT:
-      return 3;  // SPICE_MOUSE_BUTTON_RIGHT
+      return 3;
     case BTN_SIDE:
-      return 6;  // SPICE_MOUSE_BUTTON_SIDE
+      return 6;
     case BTN_EXTRA:
-      return 7;  // SPICE_MOUSE_BUTTON_EXTRA
+      return 7;
+    case BTN_FORWARD:
+      return 8;
+    case BTN_BACK:
+      return 9;
+    case BTN_TASK:
+      return 10;
   }
 
-  return 0;  // SPICE_MOUSE_BUTTON_INVALID
+  return 0;
 }
 
 static void pointerButtonHandler(void *data, struct wl_pointer *pointer,
     uint32_t serial, uint32_t time, uint32_t button, uint32_t stateW)
 {
-  button = mapWaylandToSpiceButton(button);
+  button = mapWaylandButton(button);
+  if (!button)
+    return;
 
   if (stateW == WL_POINTER_BUTTON_STATE_PRESSED)
     app_handleButtonPress(button);
diff --git a/client/displayservers/X11/x11.c b/client/displayservers/X11/x11.c
index 8c45d579..d5c544fb 100644
--- a/client/displayservers/X11/x11.c
+++ b/client/displayservers/X11/x11.c
@@ -1196,6 +1196,18 @@ static void x11UpdateKeyboardGroup(void)
     atomic_store(&x11.keyboardGroup, state.group);
 }
 
+static int x11MapButton(unsigned int button)
+{
+  if (button >= 1 && button <= 5)
+    return button;
+
+  /* X11 reserves buttons 6 and 7 for horizontal scrolling. */
+  if (button >= 8 && button < 34)
+    return button - 2;
+
+  return 0;
+}
+
 static void setFocus(bool focused, double x, double y)
 {
   if (x11.focused == focused)
@@ -1226,7 +1238,7 @@ static bool x11GetKeyLabel(int sc, char * label, size_t size)
 
 static void x11XInputEvent(XGenericEventCookie *cookie)
 {
-  static int button_state = 0;
+  static uint32_t button_state = 0;
 
   switch(cookie->evtype)
   {
@@ -1455,13 +1467,13 @@ static void x11XInputEvent(XGenericEventCookie *cookie)
         return;
 
       XIDeviceEvent *device = cookie->data;
-      if (device->detail == 4)
+      const int button = x11MapButton(device->detail);
+      if (button == 4)
         app_handleWheelMotion(-0.5);
-      else if (device->detail == 5)
+      else if (button == 5)
         app_handleWheelMotion(0.5);
-      else
-        app_handleButtonPress(
-            device->detail > 5 ? device->detail - 2 : device->detail);
+      else if (button)
+        app_handleButtonPress(button);
 
       return;
     }
@@ -1472,7 +1484,9 @@ static void x11XInputEvent(XGenericEventCookie *cookie)
         return;
 
       XIDeviceEvent *device = cookie->data;
-      app_handleButtonRelease(device->detail);
+      const int button = x11MapButton(device->detail);
+      if (button && button != 4 && button != 5)
+        app_handleButtonRelease(button);
       return;
     }
 
@@ -1482,6 +1496,9 @@ static void x11XInputEvent(XGenericEventCookie *cookie)
         return;
 
       XIRawEvent *raw = cookie->data;
+      const int button = x11MapButton(raw->detail);
+      if (!button)
+        return;
 
       /* filter out duplicate events */
       static Time         prev_time   = 0;
@@ -1491,10 +1508,9 @@ static void x11XInputEvent(XGenericEventCookie *cookie)
 
       prev_time     = raw->time;
       prev_detail   = raw->detail;
-      button_state |= (1 << raw->detail);
+      button_state |= UINT32_C(1) << button;
 
-      app_handleButtonPress(
-          raw->detail > 5 ? raw->detail - 2 : raw->detail);
+      app_handleButtonPress(button);
       return;
     }
 
@@ -1504,6 +1520,9 @@ static void x11XInputEvent(XGenericEventCookie *cookie)
         return;
 
       XIRawEvent *raw = cookie->data;
+      const int button = x11MapButton(raw->detail);
+      if (!button)
+        return;
 
       /* filter out duplicate events */
       static Time         prev_time   = 0;
@@ -1513,10 +1532,9 @@ static void x11XInputEvent(XGenericEventCookie *cookie)
 
       prev_time     = raw->time;
       prev_detail   = raw->detail;
-      button_state &= ~(1 << raw->detail);
+      button_state &= ~(UINT32_C(1) << button);
 
-      app_handleButtonRelease(
-          raw->detail > 5 ? raw->detail - 2 : raw->detail);
+      app_handleButtonRelease(button);
       return;
     }
 
diff --git a/client/include/interface/input.h b/client/include/interface/input.h
index 8b491ce9..3d8ee4a1 100644
--- a/client/include/interface/input.h
+++ b/client/include/interface/input.h
@@ -62,7 +62,7 @@ typedef struct LG_InputOps
   /* Position is in guest pixels and must be within the supplied dimensions. */
   bool (*mousePosition)(void * opaque, uint32_t x, uint32_t y,
       uint32_t width, uint32_t height);
-  /* Button order: left, middle, right, wheel up/down, side, extra. */
+  /* Button order: left, middle, right, wheel up/down, then HID buttons 4+. */
   bool (*mousePress)(void * opaque, unsigned int button);
   bool (*mouseRelease)(void * opaque, unsigned int button);
 
diff --git a/client/src/evdev.c b/client/src/evdev.c
index 2aaae55d..9909962a 100644
--- a/client/src/evdev.c
+++ b/client/src/evdev.c
@@ -211,8 +211,9 @@ static int evdev_thread(void * opaque)
         {
           case EV_KEY:
           {
-            bool isMouseBtn = ev->code >= BTN_MOUSE && ev->code <= BTN_BACK;
-            static const int mouseBtnMap[] = {1, 3, 2, 6, 7, 0, 0};
+            bool isMouseBtn =
+              ev->code >= BTN_MOUSE && ev->code <= BTN_TASK;
+            static const int mouseBtnMap[] = {1, 3, 2, 6, 7, 8, 9, 10};
 
             if (ev->value == 1)
             {
diff --git a/client/src/input_spice.c b/client/src/input_spice.c
index efaec2c9..10acb715 100644
--- a/client/src/input_spice.c
+++ b/client/src/input_spice.c
@@ -59,11 +59,17 @@ static bool spiceMouseMotion(void * opaque, int32_t x, int32_t y)
 
 static bool spiceMousePress(void * opaque, unsigned int button)
 {
+  if (button > 7)
+    return true;
+
   return purespice_mousePress(button);
 }
 
 static bool spiceMouseRelease(void * opaque, unsigned int button)
 {
+  if (button > 7)
+    return true;
+
   return purespice_mouseRelease(button);
 }