diff --git a/charon_vna/gui.py b/charon_vna/gui.py
index b2cca39..fc2668a 100644
--- a/charon_vna/gui.py
+++ b/charon_vna/gui.py
@@ -1,5 +1,6 @@
 # %% imports
 import json
+import re
 import sys
 from pathlib import Path
 from typing import List
@@ -13,6 +14,7 @@ from PySide6.QtWidgets import (
     QApplication,
     QFileDialog,
     QInputDialog,
+    QLineEdit,
     QMainWindow,
     QMenu,
     QProgressBar,
@@ -34,7 +36,7 @@ class MainWindow(QMainWindow):
 
     plots: List[PlotWidget]
 
-    def __init__(self):
+    def __init__(self, uri: str | None = None):
         super().__init__()
 
         self.config_path = DEFAULT_CONFIG
@@ -42,7 +44,12 @@ class MainWindow(QMainWindow):
             config = json.load(f)
         self._frequency = config["frequency"]
 
-        self.vna = Charon("ip:192.168.3.1", frequency=self._frequency)
+        vna_kwargs = dict(
+            frequency=self._frequency,
+        )
+        if uri is not None:
+            vna_kwargs["uri"] = uri
+        self.vna = Charon(**vna_kwargs)
 
         mpl.use("QtAgg")
 
@@ -194,7 +201,20 @@ class MainWindow(QMainWindow):
 def main() -> None:
     app = QApplication(sys.argv)
 
-    window = MainWindow()
+    try:
+        window = MainWindow()
+    except Exception as e:
+        if e.args[0] == "No device found":
+            dialog = QInputDialog()
+            text, ok = dialog.getText(None, "Pluto IP Address", "IP Address", QLineEdit.Normal, "")
+            match = re.match(r"(\d{1,3}\.){3}\d{1,3}", text)
+            if not match:
+                raise ValueError(f"Invalid IP address: {text}")
+            uri = f"ip:{text}"
+            window = MainWindow(uri=uri)
+        else:
+            raise e
+
     window.show()
 
     app.exec()