--- a/gfx/wr/webrender/src/prim_store/mod.rs
+++ b/gfx/wr/webrender/src/prim_store/mod.rs
@@ -1075,17 +1075,17 @@ impl BrushSegment {
                     device_pixel_scale,
                     frame_context.fb_config,
                 );
 
                 let clip_task_id = frame_state.render_tasks.add(clip_task);
                 let port = frame_state
                     .surfaces[surface_index.0]
                     .render_tasks
-                    .expect(&format!("bug: no task for surface {:?}", surface_index))
+                    .unwrap_or_else(|| panic!("bug: no task for surface {:?}", surface_index))
                     .port;
                 frame_state.render_tasks.add_dependency(port, clip_task_id);
                 ClipMaskKind::Mask(clip_task_id)
             }
             None => {
                 ClipMaskKind::Clipped
             }
         }

--- a/gfx/wr/webrender/src/renderer.rs
+++ b/gfx/wr/webrender/src/renderer.rs
@@ -1151,17 +1151,17 @@ impl TextureResolver {
                 };
                 let swizzle = Swizzle::default();
                 device.bind_texture(sampler, texture, swizzle);
                 swizzle
             }
             TextureSource::External(external_image) => {
                 let texture = self.external_images
                     .get(&(external_image.id, external_image.channel_index))
-                    .expect(&format!("BUG: External image should be resolved by now"));
+                    .expect("BUG: External image should be resolved by now");
                 device.bind_external_texture(sampler, texture);
                 Swizzle::default()
             }
             TextureSource::TextureCache(index, swizzle) => {
                 let texture = &self.texture_cache_map[&index];
                 device.bind_texture(sampler, texture, swizzle);
                 swizzle
             }