diff --git a/src/smooth/ftgrays.c b/src/smooth/ftgrays.c
index bff3c5903..28a081cbc 100644
--- a/src/smooth/ftgrays.c
+++ b/src/smooth/ftgrays.c
@@ -1912,7 +1912,7 @@ typedef ptrdiff_t  FT_PtrDist;
   gray_convert_glyph_inner( RAS_ARG_
                             int  continued )
   {
-    int  error;
+    volatile int  error;
 
 
     if ( ft_setjmp( ras.jump_buffer ) == 0 )