diff --git a/src/components/main/layout/construct.rs b/src/components/main/layout/construct.rs
index 4e9712caa8f7..5f999eb2663a 100644
--- a/src/components/main/layout/construct.rs
+++ b/src/components/main/layout/construct.rs
@@ -293,7 +293,9 @@ impl<'a> FlowConstructor<'a> {
         }
 
         let mut inline_flow = box InlineFlow::from_fragments((*node).clone(), fragments);
-        inline_flow.compute_minimum_ascent_and_descent(self.font_context(), &**node.style());
+        let (ascent, descent) = inline_flow.compute_minimum_ascent_and_descent(self.font_context(), &**node.style());
+        inline_flow.minimum_height_above_baseline = ascent;
+        inline_flow.minimum_depth_below_baseline = descent;
         let mut inline_flow = inline_flow as Box<Flow>;
         TextRunScanner::new().scan_for_runs(self.font_context(), inline_flow);
         let mut inline_flow = FlowRef::new(inline_flow);
diff --git a/src/components/main/layout/inline.rs b/src/components/main/layout/inline.rs
index 5f8158a0bea3..77cacb85cdcc 100644
--- a/src/components/main/layout/inline.rs
+++ b/src/components/main/layout/inline.rs
@@ -1057,15 +1057,14 @@ impl InlineFlow {
     /// construction.
     ///
     /// `style` is the style of the block.
-    pub fn compute_minimum_ascent_and_descent(&mut self,
+    pub fn compute_minimum_ascent_and_descent(&self,
                                               font_context: &mut FontContext,
-                                              style: &ComputedValues) {
+                                              style: &ComputedValues) -> (Au, Au) {
         let font_style = text::computed_style_to_font_style(style);
         let font_metrics = text::font_metrics_for_style(font_context, &font_style);
         let line_height = text::line_height_from_style(style, style.get_font().font_size);
         let inline_metrics = InlineMetrics::from_font_metrics(&font_metrics, line_height);
-        self.minimum_height_above_baseline = inline_metrics.height_above_baseline;
-        self.minimum_depth_below_baseline = inline_metrics.depth_below_baseline;
+        (inline_metrics.height_above_baseline, inline_metrics.depth_below_baseline)
     }
 }