diff --git a/.github/dependabot.yml b/.github/dependabot.yml
new file mode 100644
index 0000000..8c0202a
--- /dev/null
+++ b/.github/dependabot.yml
@@ -0,0 +1,8 @@
+version: 2
+updates:
+  # Maintain GitHub Actions
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 5
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..1483343
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,105 @@
+name: CI
+
+on:
+  push:
+  pull_request:
+
+permissions:
+  contents: read
+
+env:
+  RELEASEVER: "44"
+
+jobs:
+  format:
+    name: Check Nim formatting
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          submodules: recursive
+
+      - name: Install Nim
+        uses: jiro4989/setup-nim-action@cb1fc1270b117457dd0d9f610ec981fad3369cec # v2.3.0
+        with:
+          nim-version: "2.2.10"
+
+      - name: Check formatting
+        run: ./scripts/check-format.sh
+
+  build:
+    name: Build application
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          submodules: recursive
+
+      - name: Install system dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install --no-install-recommends -y \
+            libadwaita-1-dev \
+            libgtk-4-dev \
+            pkg-config
+
+      - name: Install Nim
+        uses: jiro4989/setup-nim-action@cb1fc1270b117457dd0d9f610ec981fad3369cec # v2.3.0
+        with:
+          nim-version: "2.2.10"
+
+      - name: Build
+        run: nimble build --define:releasever=${RELEASEVER} --verbose
+
+      - name: Prepare build artifact
+        run: |
+          if [[ ! -x ./umswitch ]]; then
+            candidate=$(find . "$HOME/.nimble/bin" \
+              -type f -name umswitch -not -path './umswitch' \
+              -print -quit 2>/dev/null || true)
+            if [[ -z "$candidate" ]]; then
+              echo "umswitch binary was not produced. Build outputs:" >&2
+              find . "$HOME/.nimble/bin" -maxdepth 4 -type f -print 2>/dev/null | sort >&2
+              exit 1
+            fi
+            cp "$candidate" ./umswitch
+          fi
+          test -x ./umswitch
+          file ./umswitch
+
+      - name: Upload binary
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        with:
+          name: umswitch
+          path: umswitch
+          if-no-files-found: error
+
+  test:
+    name: Compile tests
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          submodules: recursive
+
+      - name: Install Nim
+        uses: jiro4989/setup-nim-action@cb1fc1270b117457dd0d9f610ec981fad3369cec # v2.3.0
+        with:
+          nim-version: "2.2.10"
+
+      - name: Install test dependencies
+        run: |
+          mkdir -p /tmp/hop-test-deps
+          printf 'version = "0.0.1"\nauthor = "CI"\ndescription = "CI test dependencies"\nlicense = "MIT"\nrequires "fungus == 0.1.19"\n' > /tmp/hop-test-deps/testdeps.nimble
+          cd /tmp/hop-test-deps
+          nimble install -y
+
+      - name: Compile test program
+        run: |
+          nim c --hints:off \
+            --path:$HOME/.nimble/pkgs2/fungus-* \
+            --path:$HOME/.nimble/pkgs2/micros-* \
+            test.nim
diff --git a/scripts/check-format.sh b/scripts/check-format.sh
new file mode 100755
index 0000000..c929109
--- /dev/null
+++ b/scripts/check-format.sh
@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+repo_root=$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)
+tmp_dir=$(mktemp -d)
+trap 'rm -rf "$tmp_dir"' EXIT
+
+status=0
+while IFS= read -r -d '' file; do
+  formatted="$tmp_dir/$(basename "$file")"
+  nimpretty --out:"$formatted" "$repo_root/$file" >/dev/null
+  nimpretty "$formatted" >/dev/null
+  if ! diff -u "$repo_root/$file" "$formatted"; then
+    status=1
+  fi
+done < <(git -C "$repo_root" ls-files -z -- '*.nim')
+
+if [[ "$status" -ne 0 ]]; then
+  echo "Formatting check failed. Run nimpretty on the files above." >&2
+  exit "$status"
+fi
+
+echo "All Nim files are formatted."
diff --git a/src/backend/add.nim b/src/backend/add.nim
index ff816be..b9b5fb8 100644
--- a/src/backend/add.nim
+++ b/src/backend/add.nim
@@ -10,7 +10,8 @@ const de_to_pkgs_to_add: Table[string, seq[string]] = {
   "XFCE": @["@ultramarine-xfce-product-environment"],
 }.toTable()
 
-proc add_de_offline*(hub: ref Hub, de: string): Result[void, string] {.thread.} =
+proc add_de_offline*(hub: ref Hub, de: string): Result[void,
+    string] {.thread.} =
   ?ensure_dnf5()
   echo "Downloading packages..."
   hub.toMain.send UpdateState.init "Downloading packages..."
@@ -21,7 +22,7 @@ proc add_de_offline*(hub: ref Hub, de: string): Result[void, string] {.thread.}
   let time = now()
   var args = @["in", "-y", "--offline"]
   args &= pkgs
-  let process = startProcess("/usr/bin/dnf5", args=args, options = {poStdErrToStdOut})
+  let process = startProcess("/usr/bin/dnf5", args = args, options = {poStdErrToStdOut})
   track_dnf5_download_progress(process, some(hub))
   ?end_proc(process, time, "Downloading Packages", "arrange offline DE install")
   hub.toMain.send MsgToMain DownloadFinish.init
diff --git a/src/backend/change.nim b/src/backend/change.nim
index 36413ed..c703a4b 100644
--- a/src/backend/change.nim
+++ b/src/backend/change.nim
@@ -18,7 +18,8 @@ proc swap*(hub: ref Hub, to: string): Result[void, string] {.thread.} =
   echo "├═ New: "&to
   stdout.write "┊ "
   let time = now()
-  let process = startProcess("/usr/bin/dnf5", args=["swap", "-y", "ultramarine-release-identity", to], options = {poStdErrToStdOut})
+  let process = startProcess("/usr/bin/dnf5", args = ["swap", "-y",
+      "ultramarine-release-identity", to], options = {poStdErrToStdOut})
   track_dnf5_download_progress(process, some(hub))
   ?end_proc(process, time, "Swap Editions", "swap editions")
   hub.toMain.send MsgToMain DownloadFinish.init
diff --git a/src/backend/delete.nim b/src/backend/delete.nim
index afa3b50..b679d0a 100644
--- a/src/backend/delete.nim
+++ b/src/backend/delete.nim
@@ -11,7 +11,8 @@ const de_to_pkgs_to_rm: Table[string, seq[string]] = {
   "XFCE": @["@ultramarine-xfce-product-environment"],
 }.toTable()
 
-proc remove_de_offline*(hub: ref Hub, de: string): Result[void, string] {.thread.} =
+proc remove_de_offline*(hub: ref Hub, de: string): Result[void,
+    string] {.thread.} =
   ?ensure_dnf5()
   echo "Removing packages..."
   hub.toMain.send UpdateState.init("Running dnf5...")
@@ -22,7 +23,7 @@ proc remove_de_offline*(hub: ref Hub, de: string): Result[void, string] {.thread
   let time = now()
   var args = @["rm", "-y", "--offline"]
   args &= pkgs
-  let process = startProcess("/usr/bin/dnf5", args=args, options = {poStdErrToStdOut})
+  let process = startProcess("/usr/bin/dnf5", args = args, options = {poStdErrToStdOut})
   track_dnf5_download_progress(process, none(ref Hub))
   ?end_proc(process, time, "Remove DE Offline", "arrange offline DE remove")
   ?reboot_apply_offline hub
diff --git a/src/backend/pkgs.nim b/src/backend/pkgs.nim
index 2b9f0be..c14f83a 100644
--- a/src/backend/pkgs.nim
+++ b/src/backend/pkgs.nim
@@ -45,7 +45,8 @@ proc ensure_dnf5*(): Result[void, string] =
     return err fmt"Fail to install dnf5 ({rc=})"
   ok()
 
-proc track_dnf5_download_progress*(process: Process, hub: Option[ref Hub]) {.thread.} =
+proc track_dnf5_download_progress*(process: Process, hub: Option[
+    ref Hub]) {.thread.} =
   let outs = process.outputStream
   var line = ""
   var progress = 0.0
@@ -76,7 +77,8 @@ proc track_dnf5_download_progress*(process: Process, hub: Option[ref Hub]) {.thr
                 hub.get.toMain.send Progress.init progress
             except: discard
 
-proc end_proc*(process: Process, startTime: DateTime, action: string, errAction: string = ""): Result[void, string] {.thread.} =
+proc end_proc*(process: Process, startTime: DateTime, action: string,
+    errAction: string = ""): Result[void, string] {.thread.} =
   defer: process.close()
   let errAction = if errAction == "": action else: errAction
   let rc = process.peekExitCode
@@ -90,7 +92,7 @@ proc end_proc*(process: Process, startTime: DateTime, action: string, errAction:
   echo "end_proc finished!"
   ok()
 
-proc reboot_apply_offline*(hub: ref Hub): Result[void, string] = 
+proc reboot_apply_offline*(hub: ref Hub): Result[void, string] =
   echo "reboot_apply_offline()"
   hub.toMain.send UpdateState.init("Rebooting...")
   let rc = execCmd("dnf5 offline reboot -y")
diff --git a/src/pages/addDownload.nim b/src/pages/addDownload.nim
index 9f84d1c..d5313a9 100644
--- a/src/pages/addDownload.nim
+++ b/src/pages/addDownload.nim
@@ -13,13 +13,13 @@ viewable AddDownloadPage:
   hub: ref Hub
   first: bool = true
   progress: float = 0.0
-  
+
   hooks:
     afterBuild:
       proc redrawer(): bool =
         if state.hub[].toMain.peek > 0:
           discard redraw state
-        
+
         const KEEP_LISTENER_ACTIVE = true
         return KEEP_LISTENER_ACTIVE
       discard addGlobalTimeout(200, redrawer)
diff --git a/src/pages/changeApply.nim b/src/pages/changeApply.nim
index 3f6ead1..a4a00c2 100644
--- a/src/pages/changeApply.nim
+++ b/src/pages/changeApply.nim
@@ -18,7 +18,7 @@ viewable ChangeApplyPage:
       proc redrawer(): bool =
         if state.hub[].toMain.peek > 0:
           discard redraw state
-        
+
         const KEEP_LISTENER_ACTIVE = true
         return KEEP_LISTENER_ACTIVE
       discard addGlobalTimeout(200, redrawer)
diff --git a/src/pages/deleteReboot.nim b/src/pages/deleteReboot.nim
index 3a35e4f..2a066e4 100644
--- a/src/pages/deleteReboot.nim
+++ b/src/pages/deleteReboot.nim
@@ -16,7 +16,7 @@ viewable DeleteRebootPage:
       proc redrawer(): bool =
         if state.hub[].toMain.peek > 0:
           discard redraw state
-        
+
         const KEEP_LISTENER_ACTIVE = true
         return KEEP_LISTENER_ACTIVE
       discard addGlobalTimeout(200, redrawer)
diff --git a/src/umswitch.nim b/src/umswitch.nim
index 8dc0f3a..9f180c1 100644
--- a/src/umswitch.nim
+++ b/src/umswitch.nim
@@ -1,7 +1,8 @@
 import std/[os, osproc, sequtils, envvars, sugar]
 import owlkettle, owlkettle/adw
 import app
-import pages/[action, add, addDownload, delete, deleteReboot, change, changeApply, zNotFound, zError]
+import pages/[action, add, addDownload, delete, deleteReboot, change,
+    changeApply, zNotFound, zError]
 import backend/pkgs
 
 const
@@ -39,21 +40,25 @@ proc main =
   # let logfile = open(logfilepath, fmWrite)
   # defer: logfile.close()
   adw.brew(gui App(
-    installed_desktops=package_installed(editions.values.toSeq),
-    installed_identities=package_installed(identities.values.toSeq),
-  ), stylesheets=stylesheets)
+    installed_desktops = package_installed(editions.values.toSeq),
+    installed_identities = package_installed(identities.values.toSeq),
+  ), stylesheets = stylesheets)
 
 when isMainModule:
   if os.isAdmin():
     main()
     quit(0)
   when usesudo != 0:
-    quit findExe("sudo").startProcess(args=getAppFilename()&commandLineParams(), options={poParentStreams}).waitForExit
+    quit findExe("sudo").startProcess(args = getAppFilename()&commandLineParams(
+      ), options = {poParentStreams}).waitForExit
   # run umswitch as root via pkexec
-  discard findExe("xhost").startProcess(args=["si:localuser:root", "+localhost"], options={poParentStreams}).waitForExit
+  discard findExe("xhost").startProcess(args = ["si:localuser:root",
+      "+localhost"], options = {poParentStreams}).waitForExit
   let envs = collect:
     for k, v in envPairs():
       k&"="&v
-  let rc = findExe("pkexec").startProcess(args = @["env"]&envs&getAppFilename()&commandLineParams(), options={poParentStreams}).waitForExit
-  discard findExe("xhost").startProcess(args=["-si:localuser:root", "-localhost"], options={poParentStreams}).waitForExit
+  let rc = findExe("pkexec").startProcess(args = @["env"]&envs&getAppFilename(
+    )&commandLineParams(), options = {poParentStreams}).waitForExit
+  discard findExe("xhost").startProcess(args = ["-si:localuser:root",
+      "-localhost"], options = {poParentStreams}).waitForExit
   quit rc
diff --git a/umswitch.nimble b/umswitch.nimble
index de8521d..6944b07 100644
--- a/umswitch.nimble
+++ b/umswitch.nimble
@@ -9,12 +9,16 @@ bin           = @["umswitch"]
 
 
 import nimsutils/src/nimsutils
-import std/[syncio, strutils]
+import std/[envvars, syncio, strutils]
 
 proc get_releasever(): int =
+  let requested = getEnv("RELEASEVER")
+  if requested != "":
+    return requested.parseInt
   for l in readFile("/etc/os-release").splitLines:
     if l.starts_with("VERSION_ID="):
-      return l[11..12].parseInt
+      let version = l["VERSION_ID=".len .. ^1].strip(chars = {'"'})
+      return version.split('.')[0].parseInt
   error("cannot find VERSION_ID in /etc/os-release")
   quit 1
 
@@ -29,4 +33,4 @@ xtask r, "alias for run": setCommand "run"
 requires "nim >= 2.0.0"
 requires "https://github.com/can-lehmann/owlkettle#HEAD"
 requires "fungus"
-requires "results == 0.5.0"
\ No newline at end of file
+requires "results == 0.5.0"