diff --git a/crates/arr-probe/tests/fixtures/hlg-720p.mkv b/crates/arr-probe/tests/fixtures/hlg-720p.mkv
new file mode 100644
index 0000000..9115e12
Binary files /dev/null and b/crates/arr-probe/tests/fixtures/hlg-720p.mkv differ
diff --git a/crates/arr-probe/tests/fixtures/sdr-10bit-hevc-720p.mkv b/crates/arr-probe/tests/fixtures/sdr-10bit-hevc-720p.mkv
new file mode 100644
index 0000000..e223551
Binary files /dev/null and b/crates/arr-probe/tests/fixtures/sdr-10bit-hevc-720p.mkv differ
diff --git a/crates/arr-probe/tests/probe.rs b/crates/arr-probe/tests/probe.rs
index 3d09732..4d60d2e 100644
--- a/crates/arr-probe/tests/probe.rs
+++ b/crates/arr-probe/tests/probe.rs
@@ -86,6 +86,28 @@ async fn hdr10_comes_from_the_transfer_function() {
     assert_eq!(file.media.hdr, HdrFormat::Hdr10);
 }
 
+#[tokio::test]
+async fn hlg_comes_from_the_transfer_function() {
+    let file = Prober::new()
+        .probe(fixture("hlg-720p.mkv"))
+        .await
+        .expect("the fixture is readable");
+
+    assert_eq!(file.video_codec, "hevc");
+    assert_eq!(file.media.hdr, HdrFormat::Hlg);
+}
+
+#[tokio::test]
+async fn ten_bit_hevc_without_hdr_transfer_is_sdr() {
+    let file = Prober::new()
+        .probe(fixture("sdr-10bit-hevc-720p.mkv"))
+        .await
+        .expect("the fixture is readable");
+
+    assert_eq!(file.video_codec, "hevc");
+    assert_eq!(file.media.hdr, HdrFormat::Sdr);
+}
+
 #[tokio::test]
 async fn dolby_vision_profile_5_is_reported_as_a_number() {
     let file = Prober::new()
diff --git a/scripts/make-probe-fixtures.sh b/scripts/make-probe-fixtures.sh
index 08af9e3..66636c2 100755
--- a/scripts/make-probe-fixtures.sh
+++ b/scripts/make-probe-fixtures.sh
@@ -55,6 +55,20 @@ ffmpeg -hide_banner -loglevel error -y \
     -c:v libx265 -preset ultrafast -crf 51 \
     "$out/hdr10-2160p.mkv"
 
+# HLG and SDR both use HEVC here so transfer function, rather than codec bit
+# depth, is what distinguishes their probe results.
+ffmpeg -hide_banner -loglevel error -y \
+    -f lavfi -i "color=c=black:s=1280x720:r=24:d=1" -an \
+    -vf "format=yuv420p10le,setparams=color_primaries=bt2020:color_trc=arib-std-b67:colorspace=bt2020nc" \
+    -c:v libx265 -preset ultrafast -crf 51 \
+    "$out/hlg-720p.mkv"
+
+ffmpeg -hide_banner -loglevel error -y \
+    -f lavfi -i "color=c=black:s=1280x720:r=24:d=1" -an \
+    -vf "format=yuv420p10le" \
+    -c:v libx265 -preset ultrafast -crf 51 \
+    "$out/sdr-10bit-hevc-720p.mkv"
+
 # HEVC base layer for the two Dolby Vision clips.
 ffmpeg -hide_banner -loglevel error -y \
     -f lavfi -i "color=c=black:s=1280x720:r=24:d=1" -an \