diff --git a/adb/commandline.cpp b/adb/commandline.cpp
index 9f23473..d126f52 100644
--- a/adb/commandline.cpp
+++ b/adb/commandline.cpp
@@ -1588,9 +1588,13 @@
         } else {
             return 0;
         }
-    }
-    else if (!strcmp(argv[0], "tcpip") && argc > 1) {
-        return adb_connect_command(android::base::StringPrintf("tcpip:%s", argv[1]));
+    } else if (!strcmp(argv[0], "tcpip")) {
+        if (argc != 2) return syntax_error("tcpip requires an argument");
+        int port;
+        if (!android::base::ParseInt(argv[1], &port, 1, 65535)) {
+            return syntax_error("tcpip: invalid port: %s", argv[1]);
+        }
+        return adb_connect_command(android::base::StringPrintf("tcpip:%d", port));
     }
     else if (!strcmp(argv[0], "remount") ||
              !strcmp(argv[0], "reboot") ||
diff --git a/adb/test_adb.py b/adb/test_adb.py
index cb3e0d8..98c8a59 100644
--- a/adb/test_adb.py
+++ b/adb/test_adb.py
@@ -60,13 +60,13 @@
                              stderr=subprocess.STDOUT)
         out, _ = p.communicate()
         self.assertEqual(1, p.returncode)
-        self.assertIn('help message', out)
+        self.assertIn('requires an argument', out)
 
         p = subprocess.Popen(['adb', 'tcpip', 'foo'], stdout=subprocess.PIPE,
                              stderr=subprocess.STDOUT)
         out, _ = p.communicate()
         self.assertEqual(1, p.returncode)
-        self.assertIn('error', out)
+        self.assertIn('invalid port', out)
 
     # Helper method that reads a pipe until it is closed, then sets the event.
     def _read_pipe_and_set_event(self, pipe, event):