diff --git a/components/layout_2020/flexbox/layout.rs b/components/layout_2020/flexbox/layout.rs
index 880847617f6..f71f5da6915 100644
--- a/components/layout_2020/flexbox/layout.rs
+++ b/components/layout_2020/flexbox/layout.rs
@@ -2619,11 +2619,14 @@ impl FlexItemBox {
auto_cross_size_stretches_to_container_size: bool,
intrinsic_sizing_mode: IntrinsicSizingMode,
) -> Au {
- let mut positioning_context = PositioningContext::new_for_subtree(
- flex_context
- .positioning_context
- .collects_for_nearest_positioned_ancestor(),
- );
+ let mut positioning_context = PositioningContext::new_for_style(self.style())
+ .unwrap_or_else(|| {
+ PositioningContext::new_for_subtree(
+ flex_context
+ .positioning_context
+ .collects_for_nearest_positioned_ancestor(),
+ )
+ });
let style = self.independent_formatting_context.style();
match &self.independent_formatting_context.contents {
diff --git a/tests/wpt/meta/MANIFEST.json b/tests/wpt/meta/MANIFEST.json
index 117f1af832b..522021d0a9c 100644
--- a/tests/wpt/meta/MANIFEST.json
+++ b/tests/wpt/meta/MANIFEST.json
@@ -2599,6 +2599,13 @@
{}
]
],
+ "mixed-containing-blocks-crash.html": [
+ "f8a38e057d32e8bb8d7e143d867ca6364210ba38",
+ [
+ null,
+ {}
+ ]
+ ],
"negative-available-size-crash.html": [
"837fdaeba9ef8baeb4f2bad281bb13551d6d8ff9",
[
diff --git a/tests/wpt/tests/css/css-flexbox/mixed-containing-blocks-crash.html b/tests/wpt/tests/css/css-flexbox/mixed-containing-blocks-crash.html
new file mode 100644
index 00000000000..f8a38e057d3
--- /dev/null
+++ b/tests/wpt/tests/css/css-flexbox/mixed-containing-blocks-crash.html
@@ -0,0 +1,13 @@
+
+CSS Flexbox: Mixed containing blocks
+
+
+
+
+
+
+
+
+