diff --git a/Dockerfile.builder b/Dockerfile.builder
index 4941d22..b99fd84 100644
--- a/Dockerfile.builder
+++ b/Dockerfile.builder
@@ -31,7 +31,7 @@ RUN npm install
 
 COPY . .
 
-RUN test -n "$TAURI_SIGNING_PRIVATE_KEY"
+RUN node scripts/check-signing.mjs
 RUN nice -n 10 npm run bundle:windows
 
 RUN set -eux; \
diff --git a/Dockerfile.builder-linux b/Dockerfile.builder-linux
index 45f28a6..6c37c59 100644
--- a/Dockerfile.builder-linux
+++ b/Dockerfile.builder-linux
@@ -26,8 +26,8 @@ RUN npm install
 COPY . .
 
 RUN npm run icons
+RUN node scripts/check-signing.mjs
 RUN cargo test --manifest-path src-tauri/Cargo.toml --lib
-RUN test -n "$TAURI_SIGNING_PRIVATE_KEY"
 RUN nice -n 10 npm run bundle:linux
 
 RUN set -eux; \
diff --git a/scripts/check-signing.mjs b/scripts/check-signing.mjs
new file mode 100644
index 0000000..77c5de3
--- /dev/null
+++ b/scripts/check-signing.mjs
@@ -0,0 +1,40 @@
+import { mkdtempSync, writeFileSync, readFileSync, rmSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { join, resolve } from 'node:path';
+import { spawnSync } from 'node:child_process';
+import { createHash, createPublicKey, verify } from 'node:crypto';
+
+const temp = mkdtempSync(join(tmpdir(), 'fieldlens-signing-'));
+try {
+  if (!process.env.TAURI_SIGNING_PRIVATE_KEY) throw new Error('missing key');
+  const probe = join(temp, 'probe.txt');
+  writeFileSync(probe, 'FieldLens updater signing preflight\n', { mode: 0o600 });
+  const result = spawnSync(process.execPath, [resolve('node_modules/@tauri-apps/cli/tauri.js'), 'signer', 'sign', probe], {
+    env: process.env, stdio: 'pipe', timeout: 30000,
+  });
+  if (result.status !== 0) throw new Error('signing failed');
+  const config = JSON.parse(readFileSync('src-tauri/tauri.conf.json', 'utf8'));
+  const publicLines = Buffer.from(config.plugins.updater.pubkey, 'base64').toString().trim().split(/\r?\n/);
+  const signatureLines = Buffer.from(readFileSync(probe + '.sig', 'utf8').trim(), 'base64').toString().trim().split(/\r?\n/);
+  const pub = Buffer.from(publicLines[1], 'base64');
+  const sig = Buffer.from(signatureLines[1], 'base64');
+  if (pub.length !== 42 || sig.length !== 74 || !pub.subarray(2, 10).equals(sig.subarray(2, 10))) throw new Error('key mismatch');
+  const key = createPublicKey({
+    key: Buffer.concat([Buffer.from('302a300506032b6570032100', 'hex'), pub.subarray(10)]),
+    format: 'der', type: 'spki',
+  });
+  const algorithm = sig.subarray(0, 2).toString();
+  if (!['ED', 'Ed'].includes(algorithm)) throw new Error('unsupported signature');
+  const message = readFileSync(probe);
+  const signed = algorithm === 'ED' ? createHash('blake2b512').update(message).digest() : message;
+  if (!verify(null, signed, key, sig.subarray(10))) throw new Error('invalid signature');
+  if (!signatureLines[2].startsWith('trusted comment: ')) throw new Error('invalid comment');
+  const comment = Buffer.from(signatureLines[2].slice('trusted comment: '.length));
+  if (!verify(null, Buffer.concat([sig.subarray(10), comment]), key, Buffer.from(signatureLines[3], 'base64'))) throw new Error('invalid trusted comment');
+  console.log('Updater signing preflight passed: key, password and public key match.');
+} catch {
+  console.error('Updater signing preflight failed: check the signing key/password and configured public key.');
+  process.exitCode = 1;
+} finally {
+  rmSync(temp, { recursive: true, force: true });
+}
diff --git a/src-tauri/tauri.conf.json b/src-tauri/tauri.conf.json
index 3e655cf..296af3e 100644
--- a/src-tauri/tauri.conf.json
+++ b/src-tauri/tauri.conf.json
@@ -47,11 +47,18 @@
           "policykit-1"
         ]
       }
-    }
+    },
+    "icon": [
+      "icons/32x32.png",
+      "icons/128x128.png",
+      "icons/128x128@2x.png",
+      "icons/icon.icns",
+      "icons/icon.ico"
+    ]
   },
   "plugins": {
     "updater": {
-      "pubkey": "dW50cnVzdGVkIGNvbW1lbnQ6IG1pbmlzaWduIHB1YmxpYyBrZXk6IDAwQURCMzYxRTNGQTJBODgKUldTSUt2cmpZYk90QU1KNEtLVmgzZ1FFd1FmMnY0SU1ETVZMMVVQSE9TM2VsS1RJdDlTZHFFS3UK",
+      "pubkey": "dW50cnVzdGVkIGNvbW1lbnQ6IG1pbmlzaWduIHB1YmxpYyBrZXk6IDYwNzYwMEYwN0YwNjI4QTEKUldTaEtBWi84QUIyWUxYUVg3V0RqSDlJbVc4Ymh2TEh5dDFHZnNDUURlTjVuc09WZzdmajM1VzEK",
       "endpoints": [
         "https://fieldlens.arrowstack.dev/downloads/latest.json"
       ],