diff --git a/engine/MUNGA_L4/L4GLASSWIN.cpp b/engine/MUNGA_L4/L4GLASSWIN.cpp
index 065cdad..771a3de 100644
--- a/engine/MUNGA_L4/L4GLASSWIN.cpp
+++ b/engine/MUNGA_L4/L4GLASSWIN.cpp
@@ -57,9 +57,34 @@ enum
 	RadarSurfW  = 480, RadarSurfH = 640,	// portrait secondary/radar CRT at native (rotated 640x480)
 	RepaintTimerId       = 1,
 	RepaintMilliseconds  = 62,			// == L4PADPANEL (half the fastest lamp half-period)
-	MfdMonoTint = 0x00FFFFFF				// mono MFD phosphor colour (BGRA); tunable
+	MfdMonoTint = 0x0021FF42				// standard phosphor green rgb(33,255,66);
+										// 0x00RRGGBB, env BT_COCKPIT_TINT overrides
 };
 
+//
+// The mono-MFD phosphor tint for the glass-panel windows: the standard green
+// (MfdMonoTint), or BT_COCKPIT_TINT=RRGGBB (the SAME env the cockpit surround
+// honours -- L4VB16.cpp CkTint).  Read once.  ExpandPlaneToBGRA wants the tint
+// as 0x00RRGGBB (its palette path builds Red<<16 | Green<<8 | Blue), so the
+// hex is used verbatim -- no R5G6B5 packing (that is the surround's D3D path).
+//
+static unsigned long
+	GlassMfdTint()
+{
+	static unsigned long t = 0;
+	if (t == 0)
+	{
+		const char *e = getenv("BT_COCKPIT_TINT");
+		if (e != NULL && strlen(e) >= 6)
+			t = (unsigned long)(strtoul(e, NULL, 16) & 0x00FFFFFF);
+		else
+			t = (unsigned long)MfdMonoTint;
+		if (t == 0)
+			t = (unsigned long)MfdMonoTint;	// a literal "000000" -> green, not invisible
+	}
+	return t;
+}
+
 enum ColorClass { ClrRed, ClrYellow, ClrBlue };
 
 struct GButton
@@ -181,7 +206,7 @@ static void
 	w.title = title;
 	w.portPrimary = portP;
 	w.portAlt = portA;
-	w.monoTint = MfdMonoTint;
+	w.monoTint = (int)GlassMfdTint();		// standard green or BT_COCKPIT_TINT
 	w.rotate = 0;
 
 	BTRioBankMetrics metrics;