diff --git a/mux/fmp4/src/fmp4mux/boxes.rs b/mux/fmp4/src/fmp4mux/boxes.rs
index 322d062b9..745016153 100644
--- a/mux/fmp4/src/fmp4mux/boxes.rs
+++ b/mux/fmp4/src/fmp4mux/boxes.rs
@@ -1818,11 +1818,15 @@ pub(super) fn create_fmp4_fragment_header(
 ) -> Result<(gst::Buffer, u64), Error> {
     let mut v = vec![];
 
-    // Don't write a `styp` if this is only a chunk.
-    if !cfg.chunk {
-        let (brand, compatible_brands) =
+    // Don't write a `styp` if this is only a chunk unless it's the last.
+    if !cfg.chunk || cfg.last_fragment {
+        let (brand, mut compatible_brands) =
             brands_from_variant_and_caps(cfg.variant, cfg.streams.iter().map(|s| &s.caps));
 
+        if cfg.last_fragment {
+            compatible_brands.push(b"lmsg");
+        }
+
         write_box(&mut v, b"styp", |v| {
             // major brand
             v.extend(brand);
diff --git a/mux/fmp4/src/fmp4mux/imp.rs b/mux/fmp4/src/fmp4mux/imp.rs
index d1c75b377..0e60a9d7c 100644
--- a/mux/fmp4/src/fmp4mux/imp.rs
+++ b/mux/fmp4/src/fmp4mux/imp.rs
@@ -3211,6 +3211,7 @@ impl FMP4Mux {
                 chunk: !fragment_start,
                 streams: streams.as_slice(),
                 buffers: interleaved_buffers.as_slice(),
+                last_fragment: at_eos,
             })
             .map_err(|err| {
                 gst::error!(
diff --git a/mux/fmp4/src/fmp4mux/mod.rs b/mux/fmp4/src/fmp4mux/mod.rs
index 7b6d9dac3..995314be4 100644
--- a/mux/fmp4/src/fmp4mux/mod.rs
+++ b/mux/fmp4/src/fmp4mux/mod.rs
@@ -240,6 +240,9 @@ pub(crate) struct FragmentHeaderConfiguration<'a> {
 
     streams: &'a [FragmentHeaderStream],
     buffers: &'a [Buffer],
+
+    /// If this is for the last fragment.
+    last_fragment: bool,
 }
 
 #[derive(Debug)]