diff --git a/webif/src/lib/index.ts b/webif/src/lib/index.ts
deleted file mode 100644
index 856f2b6..0000000
--- a/webif/src/lib/index.ts
+++ /dev/null
@@ -1 +0,0 @@
-// place files you want to import through the `$lib` alias in this folder.
diff --git a/webif/src/lib/websocket.ts b/webif/src/lib/websocket.ts
new file mode 100644
index 0000000..493a429
--- /dev/null
+++ b/webif/src/lib/websocket.ts
@@ -0,0 +1,9 @@
+export const determineWebSocketUrl = () => {
+  const urlParams = new URLSearchParams(window.location.search)
+
+  // Use whatever is specified by the "ws" query parameter, default
+  // to the current host of nothing is specified. This allows us to
+  // manually define the WebSocket host when running the Svelte
+  // development server.
+  return urlParams.get('ws') || `ws://${window.location.host}`
+}
diff --git a/webif/src/routes/+page.svelte b/webif/src/routes/+page.svelte
index e3fb110..08df097 100644
--- a/webif/src/routes/+page.svelte
+++ b/webif/src/routes/+page.svelte
@@ -1,5 +1,7 @@
 <script>
   import { onMount } from 'svelte'
+  import { determineWebSocketUrl } from '$lib/websocket'
+
   import Logo from './Logo.svelte'
   import Configuration from './Configuration.svelte'
   import LastUpdate from './LastUpdate.svelte'
@@ -14,12 +16,6 @@
   let mainsSensorData
   let circuitSensorData
 
-  const determineWebSocketUrl = () => {
-    const urlParams = new URLSearchParams(window.location.search)
-
-    return urlParams.get('ws') || undefined
-  }
-
   const parseTimestamp = (sensorData) => {
     return new Date(sensorData[0].timestamp)
   }