diff --git a/mfbt/WindowsVersion.h b/mfbt/WindowsVersion.h
index 62d6074500..abc9ab59ae 100644
--- a/mfbt/WindowsVersion.h
+++ b/mfbt/WindowsVersion.h
@@ -179,6 +179,13 @@ IsWin11OrLater()
   return IsWindows10BuildOrLater(WinBuild::Win11RTM);
 }
 
+MOZ_ALWAYS_INLINE bool
+IsNotWin7PreRTM()
+{
+  return IsWin7SP1OrLater() || !IsWin7OrLater() ||
+         IsWindowsBuildOrLater(7600);
+}
+
 MOZ_ALWAYS_INLINE bool
 IsWin7AndPre2000Compatible() {
   /*