diff --git a/app/src/main/java/com/steamdeck/launcher/SessionActivity.kt b/app/src/main/java/com/steamdeck/launcher/SessionActivity.kt
index ef5133d9c..368858f3b 100644
--- a/app/src/main/java/com/steamdeck/launcher/SessionActivity.kt
+++ b/app/src/main/java/com/steamdeck/launcher/SessionActivity.kt
@@ -226,9 +226,22 @@ class SessionActivity : ComponentActivity(), SurfaceHolder.Callback {
         applyFrameGen()
     }
 
-    override fun surfaceChanged(holder: SurfaceHolder, format: Int, width: Int, height: Int) {}
+    private var surfaceW = 0
+    private var surfaceH = 0
+
+    override fun surfaceChanged(holder: SurfaceHolder, format: Int, width: Int, height: Int) {
+        val resized = surfaceW != 0 && (width != surfaceW || height != surfaceH)
+        surfaceW = width
+        surfaceH = height
+        if (resized) {
+            Log.i(TAG, "surface resized to ${width}x$height — rebinding the compositor")
+            CompositorHost.resize(holder.surface)
+        }
+    }
 
     override fun surfaceDestroyed(holder: SurfaceHolder) {
+        surfaceW = 0
+        surfaceH = 0
         CompositorHost.detach()
     }
 
diff --git a/app/src/main/java/com/steamdeck/launcher/wayland/CompositorHost.kt b/app/src/main/java/com/steamdeck/launcher/wayland/CompositorHost.kt
index fa311957c..95fbae473 100644
--- a/app/src/main/java/com/steamdeck/launcher/wayland/CompositorHost.kt
+++ b/app/src/main/java/com/steamdeck/launcher/wayland/CompositorHost.kt
@@ -48,6 +48,20 @@ object CompositorHost {
         return true
     }
 
+    /**
+     * The Surface changed size under the compositor (a foldable opening or closing). Android does
+     * not always recreate the Surface for that, and a swapchain built for the old size keeps
+     * presenting: the system then scales those buffers onto the new window, which on a Fold showed
+     * a 16:9 picture stretched to the square panel. Rebinding the window rebuilds the swapchain at
+     * the new size, and the scale mode letterboxes as it should.
+     */
+    @Synchronized
+    fun resize(surface: Surface) {
+        if (!started) return
+        WaylandCompositor.nativeSetSurface(null)
+        WaylandCompositor.nativeSetSurface(surface)
+    }
+
     /**
      * The activity is going away. The compositor keeps running with nothing to present into —
      * the guest carries on, and its next frames land on the Surface the next activity brings.