diff --git a/src/server/mod.rs b/src/server/mod.rs
index f695639..c57f19c 100644
--- a/src/server/mod.rs
+++ b/src/server/mod.rs
@@ -851,8 +851,8 @@ impl<C: XConnection> ServerState<C> {
                     ((event.y() as i32 - win.output_offset.y) as f64 / data.scale_factor) as i32,
                 );
                 popup.positioner.set_size(
-                    (event.width() as f64 / data.scale_factor) as i32,
-                    (event.height() as f64 / data.scale_factor) as i32,
+                    1.max((event.width() as f64 / data.scale_factor) as i32),
+                    1.max((event.height() as f64 / data.scale_factor) as i32),
                 );
                 popup.popup.reposition(&popup.positioner, 0);
             }
diff --git a/src/server/tests.rs b/src/server/tests.rs
index 0269cea..fa3fad2 100644
--- a/src/server/tests.rs
+++ b/src/server/tests.rs
@@ -2073,6 +2073,31 @@ fn fractional_scale_small_popup() {
         .expect("Missing popup data");
     let pos = &data.popup().positioner_state;
     assert_eq!(pos.size.unwrap(), testwl::Vec2 { x: 1, y: 1 });
+
+    f.satellite.reconfigure_window(x::ConfigureNotifyEvent::new(
+        popup,
+        popup,
+        x::WINDOW_NONE,
+        0,
+        0,
+        2,
+        1,
+        0,
+        true,
+    ));
+    f.run();
+    f.run();
+
+    let dims = f.connection().window(popup).dims;
+    assert!(dims.width > 0);
+    assert!(dims.height > 0);
+
+    let data = f
+        .testwl
+        .get_surface_data(popup_id)
+        .expect("Missing popup data");
+    let pos = &data.popup().positioner_state;
+    assert_eq!(pos.size.unwrap(), testwl::Vec2 { x: 1, y: 1 });
 }
 
 #[test]
diff --git a/testwl/src/lib.rs b/testwl/src/lib.rs
index b71c43d..f5ad426 100644
--- a/testwl/src/lib.rs
+++ b/testwl/src/lib.rs
@@ -1285,9 +1285,9 @@ impl Dispatch<XdgSurface, SurfaceId> for State {
                     client.kill(
                         dh,
                         ProtocolError {
-                            code: xdg_surface::Error::InvalidSize.into(),
-                            object_id: resource.id().protocol_id(),
-                            object_interface: XdgSurface::interface().name.to_string(),
+                            code: xdg_positioner::Error::InvalidInput.into(),
+                            object_id: positioner.id().protocol_id(),
+                            object_interface: XdgPositioner::interface().name.to_string(),
                             message,
                         },
                     );
@@ -1362,11 +1362,11 @@ impl Default for PositionerState {
 impl Dispatch<XdgPositioner, ()> for State {
     fn request(
         state: &mut Self,
-        _: &Client,
+        client: &Client,
         resource: &XdgPositioner,
         request: <XdgPositioner as Resource>::Request,
         _: &(),
-        _: &DisplayHandle,
+        handle: &DisplayHandle,
         _: &mut wayland_server::DataInit<'_, Self>,
     ) {
         let hash_map::Entry::Occupied(mut data) = state
@@ -1377,6 +1377,22 @@ impl Dispatch<XdgPositioner, ()> for State {
         };
         match request {
             xdg_positioner::Request::SetSize { width, height } => {
+                if width <= 0 || height <= 0 {
+                    // TODO: figure out why the client.kill here doesn't make satellite print the error message
+                    let message = format!("positioner had an invalid size {width}x{height}");
+                    eprintln!("{message}");
+                    client.kill(
+                        handle,
+                        ProtocolError {
+                            code: xdg_positioner::Error::InvalidInput.into(),
+                            object_id: resource.id().protocol_id(),
+                            object_interface: XdgPositioner::interface().name.to_string(),
+                            message,
+                        },
+                    );
+                    return;
+                }
+
                 data.get_mut().size = Some(Vec2 {
                     x: width,
                     y: height,