diff --git a/sys/dev/fb/vesa.c b/sys/dev/fb/vesa.c
index 0698220de78b..d51e560c7f84 100644
--- a/sys/dev/fb/vesa.c
+++ b/sys/dev/fb/vesa.c
@@ -1359,6 +1359,7 @@ vesa_set_mode(video_adapter_t *adp, int mode)
 	vesa_adp->va_crtc_addr =
 		(vesa_adp->va_flags & V_ADP_COLOR) ? COLOR_CRTC : MONO_CRTC;
 
+	vesa_adp->va_flags &= ~V_ADP_CWIDTH9;
 	vesa_adp->va_line_width = info.vi_buffer_size / info.vi_height;
 	if ((info.vi_flags & V_INFO_GRAPHICS) != 0)
 		vesa_adp->va_line_width /= info.vi_planes;
diff --git a/sys/dev/fb/vga.c b/sys/dev/fb/vga.c
index f9ef2abf3935..286202d72d0b 100644
--- a/sys/dev/fb/vga.c
+++ b/sys/dev/fb/vga.c
@@ -862,6 +862,9 @@ update_adapter_info(video_adapter_t *adp, video_info_t *info)
     /* XXX */
     adp->va_buffer = info->vi_buffer;
     adp->va_buffer_size = info->vi_buffer_size;
+    adp->va_flags &= ~V_ADP_CWIDTH9;
+    if (info->vi_flags & V_INFO_CWIDTH9)
+	adp->va_flags |= V_ADP_CWIDTH9;
     if (info->vi_mem_model == V_INFO_MM_VGAX) {
 	adp->va_line_width = info->vi_width/2;
     } else if (info->vi_flags & V_INFO_GRAPHICS) {
@@ -1221,6 +1224,29 @@ probe_adapters(void)
 	}
     }
 
+#if !defined(VGA_NO_BIOS) && !defined(VGA_NO_MODE_CHANGE)
+    /*
+     * Attempt to determine the real character width for each mode.  9 wide
+     * is supposed to be standard for EGA mono mode and most VGA text modes,
+     * but some hardware doesn't support it, so dynamic configuration is
+     * needed.  Bit 0 in sequencer register 1 is supposed control the width
+     * (set = 8), but this is unreliable too.  Trust that 0 in the sequencer
+     * bit means 9 wide after verifying that 9 is consistent with some CRTC
+     * timing. The ratio (Horizontal Total) / (Horizontal Displayed) is
+     * about 1.2 in all standard 9-wide modes and should be about 9/8 larger
+     * again  in similar 8-wide modes; in practice it is usually about 1.4
+     * times larger.
+     */
+    for (i = 0; i < nitems(bios_vmode); ++i) {
+	if (bios_vmode[i].vi_mem_model == V_INFO_MM_TEXT &&
+	    bios_vmode[i].vi_width != 90) {
+	    mp = get_mode_param(map_mode_num(bios_vmode[i].vi_mode));
+	    if (mp != NULL && !(mp[5] & 1) && mp[10] <= mp[11] * 125 / 100)
+		bios_vmode[i].vi_flags |= V_INFO_CWIDTH9;
+	}
+    }
+#endif
+
     /* buffer address */
     vga_get_info(&biosadapter[V_ADP_PRIMARY],
 		 biosadapter[V_ADP_PRIMARY].va_initial_mode, &info);
diff --git a/sys/sys/fbio.h b/sys/sys/fbio.h
index 0d16402cb077..4aea3c37ab7d 100644
--- a/sys/sys/fbio.h
+++ b/sys/sys/fbio.h
@@ -338,6 +338,7 @@ struct video_info {
 #define V_INFO_LINEAR	(1 << 2)
 #define V_INFO_VESA	(1 << 3)
 #define	V_INFO_NONVGA	(1 << 4)
+#define	V_INFO_CWIDTH9	(1 << 5)
     int			vi_width;
     int			vi_height;
     int			vi_cwidth;
@@ -400,6 +401,7 @@ struct video_adapter {
 #define V_ADP_REGISTERED (1 << 18)
 #define V_ADP_ATTACHED	(1 << 19)
 #define	V_ADP_DAC8	(1 << 20)
+#define	V_ADP_CWIDTH9	(1 << 21)
     vm_offset_t		va_io_base;
     int			va_io_size;
     vm_offset_t		va_crtc_addr;