diff --git a/include/freetype/internal/ftcalc.h b/include/freetype/internal/ftcalc.h
index 46e7f22..e228617 100644
--- a/include/freetype/internal/ftcalc.h
+++ b/include/freetype/internal/ftcalc.h
@@ -401,20 +401,31 @@ FT_BEGIN_HEADER
 
     _BitScanReverse( &where, x );
 
     return (FT_Int32)where;
   }
 
 #define FT_MSB( x )  FT_MSB_i386( x )
 
 #endif
 
+#elif defined( __WATCOMC__ ) && defined( __386__ )
+
+extern __inline FT_Int32 FT_MSB_i386(FT_UInt32);
+#pragma aux FT_MSB_i386 = \
+  "bsr eax, eax" \
+  parm [eax] nomemory \
+  value [eax] \
+  modify exact [eax] nomemory;
+
+#define FT_MSB( x )  FT_MSB_i386( x )
+
 #elif defined( __DECC ) || defined( __DECCXX )
 
 #include <builtins.h>
 
 #define FT_MSB( x )  (FT_Int)( 63 - _leadz( x ) )
 
 #elif defined( _CRAYC )
 
 #include <intrinsics.h>