diff --git a/docker_healthcheck.js b/docker_healthcheck.js
index 7c8258ba6..c5d255595 100755
--- a/docker_healthcheck.js
+++ b/docker_healthcheck.js
@@ -11,7 +11,8 @@ if (config.https) {
 const port = require('./src/services/port');
 const host = require('./src/services/host');
 
-let options = {timeout: 2000};
+const options = { timeout: 2000 };
+
 const callback = res => {
     console.log(`STATUS: ${res.statusCode}`);
     if (res.statusCode === 200) {
@@ -20,7 +21,9 @@ const callback = res => {
         process.exit(1);
     }
 };
+
 let request;
+
 if (port !== 0) { // TCP socket.
     const url = `http://${host}:${port}/api/health-check`;
     request = http.request(url, options, callback);
@@ -29,6 +32,7 @@ if (port !== 0) { // TCP socket.
     options.path = '/api/health-check';
     request = http.request(options, callback);
 }
+
 request.on("error", err => {
     console.log("ERROR");
     process.exit(1);
diff --git a/src/services/port.js b/src/services/port.js
index bba42b7c7..c57f22a5d 100644
--- a/src/services/port.js
+++ b/src/services/port.js
@@ -6,8 +6,8 @@ const dataDir = require('./data_dir');
 function parseAndValidate(portStr, source) {
     const portNum = parseInt(portStr);
 
-    if (!portNum && portNum !== 0 || portNum < 0 || portNum >= 65536) {
-        console.log(`FATAL ERROR: Invalid port value "${portStr}" from ${source}, should be a number between 0 and 65536.`);
+    if (isNaN(portNum) || portNum < 0 || portNum >= 65536) {
+        console.log(`FATAL ERROR: Invalid port value "${portStr}" from ${source}, should be an integer between 0 and 65536.`);
         process.exit(-1);
     }
 
diff --git a/src/www b/src/www
index 1bf484520..136feabf3 100644
--- a/src/www
+++ b/src/www
@@ -100,14 +100,14 @@ async function startTrilium() {
      */
 
     httpServer.keepAliveTimeout = 120000 * 5;
-    const listenTcp = port !== 0;
-    if (listenTcp) {
+    const listenOnTcp = port !== 0;
+    if (listenOnTcp) {
       httpServer.listen(port, host); // TCP socket.
     } else {
       httpServer.listen(host); // Unix socket.
     }
     httpServer.on('error', error => {
-            if (!listenTcp || error.syscall !== 'listen') {
+            if (!listenOnTcp || error.syscall !== 'listen') {
                 throw error;
             }
 
@@ -130,7 +130,7 @@ async function startTrilium() {
     )
 
     httpServer.on('listening', () => {
-        if (listenTcp) {
+        if (listenOnTcp) {
             log.info(`Listening on port ${port}`)
         } else {
             log.info(`Listening on unix socket ${host}`)