diff --git a/src/ftfont.c b/src/ftfont.c

index 4ebc4be..bac9a4f 100644

--- a/src/ftfont.c

+++ b/src/ftfont.c

@@ -1262,7 +1262,7 @@ ftfont_open (f, entity, pixel_size)

     spacing = XINT (AREF (entity, FONT_SPACING_INDEX));

   else

     spacing = FC_PROPORTIONAL;

-  if (spacing != FC_PROPORTIONAL)

+  if (spacing != FC_PROPORTIONAL && spacing != FC_DUAL)

     font->min_width = font->average_width = font->space_width

       = (scalable ? ft_face->max_advance_width * size / upEM

 	 : ft_face->size->metrics.max_advance >> 6);

diff --git a/src/xftfont.c b/src/xftfont.c

index 82701ce..e74ce31 100644

--- a/src/xftfont.c

+++ b/src/xftfont.c

@@ -418,7 +418,7 @@ xftfont_open (f, entity, pixel_size)

 	ascii_printable[i] = ' ' + i;

     }

   BLOCK_INPUT;

-  if (spacing != FC_PROPORTIONAL)

+  if (spacing != FC_PROPORTIONAL && spacing != FC_DUAL)

     {

       font->min_width = font->average_width = font->space_width

 	= xftfont->max_advance_width;