diff --git a/packages/fcl-image/src/bmpcomn.pp b/packages/fcl-image/src/bmpcomn.pp
index e1866fa650..c93c4580be 100644
--- a/packages/fcl-image/src/bmpcomn.pp
+++ b/packages/fcl-image/src/bmpcomn.pp
@@ -29,6 +29,7 @@ const
   BI_BITFIELDS = 3;
   BI_JPEG = 4;
   BI_PNG = 5;
+  BI_ALPHABITFIELDS = 6;  // WINCE5+, sometimes also abused by others.
 
 type