diff --git a/ports/servoshell/desktop/app_state.rs b/ports/servoshell/desktop/app_state.rs
index 6bbc124d8e5..e72580074b8 100644
--- a/ports/servoshell/desktop/app_state.rs
+++ b/ports/servoshell/desktop/app_state.rs
@@ -8,7 +8,7 @@ use std::path::PathBuf;
 use std::rc::Rc;
 
 use euclid::Vector2D;
-use image::DynamicImage;
+use image::{DynamicImage, ImageFormat};
 use keyboard_types::{Key, KeyboardEvent, Modifiers, ShortcutMatcher};
 use log::{error, info};
 use servo::base::id::WebViewId;
@@ -146,7 +146,10 @@ impl RunningAppState {
             return;
         };
 
-        if let Err(error) = DynamicImage::ImageRgba8(image).save(output_path) {
+        let image_format = ImageFormat::from_path(output_path).unwrap_or(ImageFormat::Png);
+        if let Err(error) =
+            DynamicImage::ImageRgba8(image).save_with_format(output_path, image_format)
+        {
             error!("Failed to save {output_path}: {error}.");
         }
     }
diff --git a/tests/wpt/meta/MANIFEST.json b/tests/wpt/meta/MANIFEST.json
index a920226f3f1..ef97c1ac50c 100644
--- a/tests/wpt/meta/MANIFEST.json
+++ b/tests/wpt/meta/MANIFEST.json
@@ -506162,7 +506162,7 @@
         []
        ],
        "executorservo.py": [
-        "2710b1b844c8e93c251c91c8809697d357bd4f06",
+        "e3369d24ebc6d6aac1b4632ef673a36602417745",
         []
        ],
        "executorservodriver.py": [
diff --git a/tests/wpt/tests/tools/wptrunner/wptrunner/executors/executorservo.py b/tests/wpt/tests/tools/wptrunner/wptrunner/executors/executorservo.py
index 2710b1b844c..e3369d24ebc 100644
--- a/tests/wpt/tests/tools/wptrunner/wptrunner/executors/executorservo.py
+++ b/tests/wpt/tests/tools/wptrunner/wptrunner/executors/executorservo.py
@@ -226,7 +226,6 @@ class ServoRefTestExecutor(ServoExecutor):
 
     def screenshot(self, test, viewport_size, dpi, page_ranges):
         with TempFilename(self.tempdir) as output_path:
-            output_path = f"{output_path}.png"
             extra_args = ["--exit",
                           "--output=%s" % output_path,
                           "--window-size", viewport_size or "800x600"]