diff --git a/crates/egui/src/containers/popup.rs b/crates/egui/src/containers/popup.rs
index 2a9335ede..080c00bd1 100644
--- a/crates/egui/src/containers/popup.rs
+++ b/crates/egui/src/containers/popup.rs
@@ -571,6 +571,7 @@ impl<'a> Popup<'a> {
             .fixed_pos(anchor)
             .sense(sense)
             .layout(layout)
+            .sizing_pass(!was_open_last_frame)
             .info(info.unwrap_or_else(|| {
                 UiStackInfo::new(kind.into()).with_tag_value(
                     MenuConfig::MENU_CONFIG_TAG,
diff --git a/crates/egui_kittest/tests/popup.rs b/crates/egui_kittest/tests/popup.rs
index a8d3bcc9d..4dbe33909 100644
--- a/crates/egui_kittest/tests/popup.rs
+++ b/crates/egui_kittest/tests/popup.rs
@@ -1,5 +1,72 @@
+use egui::{Align, Layout, Popup};
+use egui_kittest::Harness;
 use kittest::Queryable as _;
 
+#[test]
+fn reopened_popup_resizes_for_wider_items() {
+    const POPUP_BUTTON: &str = "Dynamic popup";
+    const SHORT_ITEM: &str = "Short item";
+    const WIDE_ITEM: &str = "Newly added item with a much wider label";
+
+    #[derive(Default)]
+    struct State {
+        open: bool,
+        show_wide_item: bool,
+    }
+
+    let mut harness = Harness::builder()
+        .with_size(egui::Vec2::new(500.0, 300.0))
+        .build_ui_state(
+            |ui, state| {
+                let response = ui.button(POPUP_BUTTON);
+                if response.clicked() {
+                    state.open = !state.open;
+                }
+
+                Popup::from_response(&response)
+                    .open(state.open)
+                    .layout(Layout::top_down_justified(Align::Min))
+                    .show(|ui| {
+                        _ = ui.selectable_label(false, SHORT_ITEM);
+                        _ = ui.selectable_label(false, "Another short item");
+                        if state.show_wide_item {
+                            _ = ui.selectable_label(false, WIDE_ITEM);
+                        }
+                    });
+            },
+            State::default(),
+        );
+
+    harness.get_by_label(POPUP_BUTTON).click();
+    harness.run();
+    let initial_row_size = harness.get_by_label(SHORT_ITEM).rect().size();
+
+    harness.get_by_label(POPUP_BUTTON).click();
+    harness.run();
+    assert!(harness.query_by_label(SHORT_ITEM).is_none());
+
+    harness.state_mut().show_wide_item = true;
+    harness.run();
+    harness.get_by_label(POPUP_BUTTON).click();
+    harness.run();
+
+    let reopened_row_size = harness.get_by_label(SHORT_ITEM).rect().size();
+    let wide_row_size = harness.get_by_label(WIDE_ITEM).rect().size();
+
+    assert!(
+        reopened_row_size.x > initial_row_size.x,
+        "reopened row width ({}) did not grow beyond its initial width ({})",
+        reopened_row_size.x,
+        initial_row_size.x
+    );
+    assert!(
+        wide_row_size.y <= initial_row_size.y + 0.5,
+        "new row height ({}) exceeds the single-line row height ({})",
+        wide_row_size.y,
+        initial_row_size.y
+    );
+}
+
 #[test]
 fn test_interactive_tooltip() {
     struct State {