diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 294330f..89acaae 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -3,3 +3,5 @@ include:
   project: QubesOS/qubes-continuous-integration
 - file: /r4.3/gitlab-host.yml
   project: QubesOS/qubes-continuous-integration
+- file: /r4.3/gitlab-vm.yml
+  project: QubesOS/qubes-continuous-integration
diff --git a/.qubesbuilder b/.qubesbuilder
index 625e9c2..8bf6f63 100644
--- a/.qubesbuilder
+++ b/.qubesbuilder
@@ -2,6 +2,10 @@ host:
   rpm:
     build:
     - xorg-x11-server.spec
+vm:
+  rpm:
+    build:
+    - xorg-x11-server.spec
 source:
   files:
   - url: https://www.x.org/pub/individual/xserver/xorg-server-@VERSION@.tar.xz
diff --git a/0001-Xephyr-fix-setting-physical-output-size.patch b/0001-Xephyr-fix-setting-physical-output-size.patch
new file mode 100644
index 0000000..9130a65
--- /dev/null
+++ b/0001-Xephyr-fix-setting-physical-output-size.patch
@@ -0,0 +1,120 @@
+From 6bd9aec85f329def9ed97956d13f990bb8fbd7eb Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?=
+ <marmarek@invisiblethingslab.com>
+Date: Wed, 17 Jun 2026 20:22:20 +0200
+Subject: [PATCH] Xephyr: fix setting physical output size
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Providing physical size via RRRegisterSize() is not enough - physical
+size is a property of the output, not resolution and needs to be set
+separately. Furhermore, get the physical output size using RandR if
+-output is used, to match specific output, not the whole screen.
+
+With this, `Xephyr -output OUTPUT_NAME` properly copies not only
+resolution but also physical size of the named output.
+
+Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
+---
+ hw/kdrive/ephyr/ephyr.c |  8 ++++++++
+ hw/kdrive/ephyr/ephyr.h |  1 +
+ hw/kdrive/ephyr/hostx.c | 15 +++++++++++----
+ hw/kdrive/ephyr/hostx.h |  3 ++-
+ 4 files changed, 22 insertions(+), 5 deletions(-)
+
+diff --git a/hw/kdrive/ephyr/ephyr.c b/hw/kdrive/ephyr/ephyr.c
+index 069270219..e62c46912 100644
+--- a/hw/kdrive/ephyr/ephyr.c
++++ b/hw/kdrive/ephyr/ephyr.c
+@@ -453,6 +453,14 @@ ephyrRandRGetInfo(ScreenPtr pScreen, Rotation * rotations)
+                            screen->width,
+                            screen->height, screen->width_mm, screen->height_mm);
+ 
++    if (hostx_want_fullscreen()) {
++        RROutputPtr pOutput = RRFirstOutput(pScreen);
++        if (pOutput)
++            RROutputSetPhysicalSize(pOutput,
++                                    scrpriv->win_width_mm,
++                                    scrpriv->win_height_mm);
++    }
++
+     randr = KdSubRotation(scrpriv->randr, screen->randr);
+ 
+     RRSetCurrentConfig(pScreen, randr, 0, pSize);
+diff --git a/hw/kdrive/ephyr/ephyr.h b/hw/kdrive/ephyr/ephyr.h
+index 8833de8a9..67e24b3e8 100644
+--- a/hw/kdrive/ephyr/ephyr.h
++++ b/hw/kdrive/ephyr/ephyr.h
+@@ -76,6 +76,7 @@ typedef struct _ephyrScrPriv {
+     Bool win_explicit_position;
+     int win_x, win_y;
+     int win_width, win_height;
++    int win_width_mm, win_height_mm;
+     int server_depth;
+     const char *output;         /* Set via -output option */
+     unsigned char *fb_data;     /* only used when host bpp != server bpp */
+diff --git a/hw/kdrive/ephyr/hostx.c b/hw/kdrive/ephyr/hostx.c
+index b7ac56d50..78e957176 100644
+--- a/hw/kdrive/ephyr/hostx.c
++++ b/hw/kdrive/ephyr/hostx.c
+@@ -238,7 +238,8 @@ hostx_want_preexisting_window(KdScreenInfo *screen)
+ void
+ hostx_get_output_geometry(const char *output,
+                           int *x, int *y,
+-                          int *width, int *height)
++                          int *width, int *height,
++                          int *width_mm, int *height_mm)
+ {
+     int i, name_len = 0, output_found = FALSE;
+     char *name = NULL;
+@@ -331,6 +332,8 @@ hostx_get_output_geometry(const char *output,
+             *y = crtc_info_r->y;
+             *width = crtc_info_r->width;
+             *height = crtc_info_r->height;
++            *width_mm = output_info_r->mm_width;
++            *height_mm = output_info_r->mm_height;
+ 
+             free(crtc_info_r);
+         }
+@@ -628,8 +631,10 @@ hostx_init(void)
+                                 "(ctrl+shift grabs mouse and keyboard)");
+ 
+             if (HostX.use_fullscreen) {
+-                scrpriv->win_width  = xscreen->width_in_pixels;
+-                scrpriv->win_height = xscreen->height_in_pixels;
++                scrpriv->win_width     = xscreen->width_in_pixels;
++                scrpriv->win_height    = xscreen->height_in_pixels;
++                scrpriv->win_width_mm  = xscreen->width_in_millimeters;
++                scrpriv->win_height_mm = xscreen->height_in_millimeters;
+ 
+                 hostx_set_fullscreen_hint();
+             }
+@@ -638,7 +643,9 @@ hostx_init(void)
+                                           &scrpriv->win_x,
+                                           &scrpriv->win_y,
+                                           &scrpriv->win_width,
+-                                          &scrpriv->win_height);
++                                          &scrpriv->win_height,
++                                          &scrpriv->win_width_mm,
++                                          &scrpriv->win_height_mm);
+ 
+                 HostX.use_fullscreen = TRUE;
+                 hostx_set_fullscreen_hint();
+diff --git a/hw/kdrive/ephyr/hostx.h b/hw/kdrive/ephyr/hostx.h
+index 8b3caf245..00891a07a 100644
+--- a/hw/kdrive/ephyr/hostx.h
++++ b/hw/kdrive/ephyr/hostx.h
+@@ -84,7 +84,8 @@ xcb_cursor_t
+ void
+  hostx_get_output_geometry(const char *output,
+                            int *x, int *y,
+-                           int *width, int *height);
++                           int *width, int *height,
++                           int *width_mm, int *height_mm);
+ 
+ void
+  hostx_use_fullscreen(void);
+-- 
+2.54.0
+
diff --git a/version b/version
index 7ddb47f..51e4dc9 100644
--- a/version
+++ b/version
@@ -1 +1 @@
-21.1.21
+21.1.23
diff --git a/xorg-server-21.1.21.tar.xz.sha512 b/xorg-server-21.1.21.tar.xz.sha512
deleted file mode 100644
index 5940696..0000000
--- a/xorg-server-21.1.21.tar.xz.sha512
+++ /dev/null
@@ -1 +0,0 @@
-bb2eb4e6756eb9e38b61bd47c017da44bcf5f45f2b7a906b4bb3a56b3d791cec64abb9bf37b224efe1e4fab9cc296f3672c9b2f8e00e1cdfc54337bef63cd16c
diff --git a/xorg-server-21.1.23.tar.xz.sha512 b/xorg-server-21.1.23.tar.xz.sha512
new file mode 100644
index 0000000..8259aa5
--- /dev/null
+++ b/xorg-server-21.1.23.tar.xz.sha512
@@ -0,0 +1 @@
+7eae854af1b5db1f5d1e59cb9d26b86d98fa176d4f80f70935c707f17982d0446a0a8ad8d29c922edbd208435f995b027604fbb72e62a7bf3ba79f2f570aa0bb
diff --git a/xorg-x11-server.spec.in b/xorg-x11-server.spec.in
index 15e40ca..8cbfaa9 100644
--- a/xorg-x11-server.spec.in
+++ b/xorg-x11-server.spec.in
@@ -45,6 +45,8 @@ Patch3:     0001-Fedora-hack-Make-the-suid-root-wrapper-always-start-.patch
 Patch6:     0001-xfree86-fix-enumerating-resolutions-on-NovaCustom-V5.patch
 # backport necessary for the above patch to be effective
 Patch7:     0002-hw-xfree86-re-calculate-the-clock-and-refresh-rate.patch
+# needed for proper DPI detection in sys-gui
+Patch8:     0001-Xephyr-fix-setting-physical-output-size.patch
 
 BuildRequires:  bison
 BuildRequires:  flex
@@ -346,6 +348,7 @@ find %{inst_srcdir}/hw/xfree86 -name \*.c -delete
 # Remove unwanted files/dirs
 find %{buildroot} -type f -name '*.la' -delete
 
+%files
 
 %files common
 %doc COPYING