diff --git a/.github/workflows/build.tcl b/.github/workflows/build.tcl
new file mode 100755
index 00000000..3987a3d6
--- /dev/null
+++ b/.github/workflows/build.tcl
@@ -0,0 +1,58 @@
+#!/usr/bin/expect
+
+set timeout 60
+spawn sh boot/qemu -ci
+
+# Boot up
+expect "Selection: "
+send "4\r"
+expect "bootfile: "
+send "2\r"
+expect "term% "
+
+proc terminate {status} {
+	# Halt
+	expect "term% "
+	send "fshalt\r"
+	expect "done halting"
+
+	# Enter QEMU monitor
+	send "\x1d" ; # Ctrl+Alt+2
+	send "close\r"
+
+	exit $status
+}
+
+# Build sources
+send "cd /sys/src\r"
+expect "term% "
+
+set timeout [expr 10*60]
+send "objtype=386 mk libs cleanlibs\r"
+expect {
+	timeout {
+		puts stderr "timeout"
+		exit 1
+	}
+	-re "mk: (.+): exit status=(.+)" {
+		terminate 1
+	}
+	"term% "
+}
+
+set timeout [expr 2*60*60]
+send "mk release\r"
+expect {
+	timeout {
+		puts stderr "timeout"
+		exit 1
+	}
+	-re "mk: (.+): exit status=(.+)" {
+		terminate 1
+	}
+	"term% "
+}
+
+set timeout 60
+send "echo XXX:\$status\r"
+terminate 0
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
new file mode 100644
index 00000000..5c3390d1
--- /dev/null
+++ b/.github/workflows/build.yml
@@ -0,0 +1,24 @@
+name: Build
+
+on:
+  pull_request:
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+    - name: Setup qemu
+      run: |
+        sudo apt update
+        sudo apt -y install qemu-kvm expect
+    - name: Install plan9 binaries from the latest release
+      run: |
+        gh release download --pattern=x86.tar.gz
+        tar zxf x86.tar.gz
+        rm -f x86.tar.gz
+      env:
+        GH_TOKEN: ${{ github.token }}
+    - name: Run tests
+      run: |
+        ./boot/mkdirs
+        ./.github/workflows/build.tcl
diff --git a/boot/qemu b/boot/qemu
index decf6b27..8a20bae2 100755
--- a/boot/qemu
+++ b/boot/qemu
@@ -4,6 +4,7 @@ set -e
 cd $(dirname $0)
 
 pxe=pxeboot.raw
+display=gtk
 vmdisk=false
 case "$1" in
 -pxenew)
@@ -13,13 +14,18 @@ case "$1" in
 -mini)
 	pxe=mini.raw
 	shift
+	;;
+-ci)
+	display=none
+	shift
+	;;
 esac
 
 case "$#" in
 0)
 	;;
 *)
-	echo 'usage: boot/qemu [-pxenew]' >&2
+	echo 'usage: boot/qemu [-pxenew] [-mini] [-ci]' >&2
 	exit 1
 esac
 
@@ -30,7 +36,7 @@ u9fs="guestfwd=tcp:10.0.2.1:564-cmd:../sys/src/cmd/unix/u9fs/u9fs -a none -u $US
 tftp='tftp=..'
 mac=mac=52:54:00:12:34:56
 
-qemu-system-x86_64 -m 1G -smp 1 -serial stdio \
+qemu-system-x86_64 -m 1G -smp 1 -serial stdio -display $display \
 	-drive file=$pxe,format=raw -snapshot \
 	-device virtio-net-pci,netdev=net0,$mac \
 	-netdev "user,id=net0,$u9fs,$tftp"
diff --git a/cfg/pxe/525400123456 b/cfg/pxe/525400123456
index 121568c7..a97a299b 100644
--- a/cfg/pxe/525400123456
+++ b/cfg/pxe/525400123456
@@ -29,7 +29,7 @@ sysname=gnot
 partition=new
 factotumopts=-n
 user=glenda
-console=0
+console=0 b115200 l8 pn s1
 mouseport=ps2intellimouse
 monitor=vesa
 *nomp=1