diff --git a/widget/windows/nsWindow.cpp b/widget/windows/nsWindow.cpp
index fa747942731..790393cdd55 100644
--- a/widget/windows/nsWindow.cpp
+++ b/widget/windows/nsWindow.cpp
@@ -4578,6 +4578,13 @@ bool nsWindow::ProcessMessage(UINT msg, WPARAM &wParam, LPARAM &lParam,
 
     case WM_FONTCHANGE:
     {
+      // We only handle this message for the hidden window,
+      // as we only need to update the (global) font list once
+      // for any given change, not once per window!
+      if (mWindowType != eWindowType_invisible) {
+        break;
+      }
+
       nsresult rv;
       bool didChange = false;