diff --git a/additions/juggler/TargetRegistry.js b/additions/juggler/TargetRegistry.js
index 32eaf45..7c0a222 100644
--- a/additions/juggler/TargetRegistry.js
+++ b/additions/juggler/TargetRegistry.js
@@ -1024,6 +1024,15 @@ class BrowserContext {
   }
 
   async setDefaultViewport(viewport) {
+    // Camoufox: only override the set viewport if a new one was passed
+    if (
+      ChromeUtils.camouGetInt("window.innerWidth")
+      || ChromeUtils.camouGetInt("window.innerHeight")
+    ) {
+      if (viewport.viewportSize?.width == 1280 && viewport.viewportSize?.height == 720) {
+        return;
+      }
+    }
     this.defaultViewportSize = viewport ? viewport.viewportSize : undefined;
     this.deviceScaleFactor = viewport ? viewport.deviceScaleFactor : undefined;
     await Promise.all(Array.from(this.pages).map(page => page.updateViewportSize()));
diff --git a/additions/juggler/protocol/PageHandler.js b/additions/juggler/protocol/PageHandler.js
index 0f68344..d1f94a6 100644
--- a/additions/juggler/protocol/PageHandler.js
+++ b/additions/juggler/protocol/PageHandler.js
@@ -86,8 +86,8 @@ class PageHandler {
     
     // Try to fetch the viewport size
     this._defaultCursorPos = {
-      x: random_val(this._pageTarget._viewportSize.width),
-      y: random_val(this._pageTarget._viewportSize.height),
+      x: random_val(this._pageTarget._viewportSize?.width || 1280),
+      y: random_val(this._pageTarget._viewportSize?.height || 720),
     };
     this._lastMousePosition = { ...this._defaultCursorPos };
     this._lastTrackedPos = { ...this._defaultCursorPos };