diff --git a/app/src/main/java/org/traccar/client/MainActivity.java b/app/src/main/java/org/traccar/client/MainActivity.java
index 38f93f5..d1d0e55 100644
--- a/app/src/main/java/org/traccar/client/MainActivity.java
+++ b/app/src/main/java/org/traccar/client/MainActivity.java
@@ -290,13 +290,8 @@ public class MainActivity extends PreferenceActivity implements OnSharedPreferen
     }
 
     private boolean validateServerURL(String userUrl) {
-        if (userUrl == null || userUrl.trim().length() == 0) {
-            EditTextPreference preference = (EditTextPreference) findPreference(KEY_URL);
-            preference.setText(getString(R.string.settings_url_default_value));
-            return false;
-        }
         int port = Uri.parse(userUrl).getPort();
-        if (URLUtil.isValidUrl(userUrl) && (port >= -1 && port <= 65535)
+        if (URLUtil.isValidUrl(userUrl) && (port == -1 || (port > 0 && port <= 65535))
                 && (URLUtil.isHttpUrl(userUrl) || URLUtil.isHttpsUrl(userUrl))) {
             return true;
         }
diff --git a/app/src/main/java/org/traccar/client/ProtocolFormatter.java b/app/src/main/java/org/traccar/client/ProtocolFormatter.java
index c32782d..cd85f31 100644
--- a/app/src/main/java/org/traccar/client/ProtocolFormatter.java
+++ b/app/src/main/java/org/traccar/client/ProtocolFormatter.java
@@ -38,10 +38,7 @@ public class ProtocolFormatter {
         if (alarm != null) {
             builder.appendQueryParameter("alarm", alarm);
         }
-        int port = serverUrl.getPort();
-        if (port == -1) {
-            builder.encodedAuthority(serverUrl.getHost() + ":" + 5055);
-        }
+
         return builder.build().toString();
     }
 }
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 8b07349..ef47cf3 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -8,7 +8,7 @@
   <string name="settings_id_title">Device identifier</string>
   <string name="settings_url_title">Server URL</string>
   <string name="settings_url_summary">Tracking server URL</string>
-  <string name="settings_url_default_value" translatable="false">http://demo.traccar.org</string>
+  <string name="settings_url_default_value" translatable="false">http://demo.traccar.org:5055</string>
   <string name="settings_interval_title">Frequency</string>
   <string name="settings_interval_summary">Reporting interval in seconds</string>
   <string name="settings_distance_title">Distance</string>
diff --git a/app/src/test/java/org/traccar/client/ProtocolFormatterTest.java b/app/src/test/java/org/traccar/client/ProtocolFormatterTest.java
index 6170f02..2b4f230 100644
--- a/app/src/test/java/org/traccar/client/ProtocolFormatterTest.java
+++ b/app/src/test/java/org/traccar/client/ProtocolFormatterTest.java
@@ -22,7 +22,7 @@ public class ProtocolFormatterTest {
         Position position = new Position("123456789012345", new Location("gps"), 0);
         position.setTime(new Date(0));
 
-        String url = ProtocolFormatter.formatRequest("http://localhost", position);
+        String url = ProtocolFormatter.formatRequest("http://localhost:5055", position);
         assertEquals("http://localhost:5055?id=123456789012345&timestamp=0&lat=0.0&lon=0.0&speed=0.0&bearing=0.0&altitude=0.0&batt=0.0", url);
     }