--- a/dom/gamepad/windows/WindowsGamepad.cpp
+++ b/dom/gamepad/windows/WindowsGamepad.cpp
@@ -855,16 +855,21 @@ WindowsGamepadService::HandleRawInput(HR
   }
 
   nsTArray<bool> buttons(gamepad->numButtons);
   buttons.SetLength(gamepad->numButtons);
   // If we don't zero out the buttons array first, sometimes it can reuse values.
   memset(buttons.Elements(), 0, gamepad->numButtons * sizeof(bool));
 
   for (unsigned i = 0; i < usageLength; i++) {
+    // The button index in usages may be larger than what we detected when
+    // enumerating gamepads. If so, warn and continue.
+    if (NS_WARN_IF((usages[i] - 1) >= buttons.Length())) {
+      continue;
+    }
     buttons[usages[i] - 1] = true;
   }
 
   if (gamepad->hasDpad) {
     // Get d-pad position as 4 buttons.
     ULONG value;
     if (mHID.mHidP_GetUsageValue(HidP_Input, gamepad->dpadCaps.UsagePage, 0, gamepad->dpadCaps.Range.UsageMin, &value, parsed, (PCHAR)raw->data.hid.bRawData, raw->data.hid.dwSizeHid) == HIDP_STATUS_SUCCESS) {
       UnpackDpad(static_cast<LONG>(value), gamepad, buttons);