diff --git a/crates/pptx/src/read/timing.rs b/crates/pptx/src/read/timing.rs
index fcf01953..f331ecfe 100644
--- a/crates/pptx/src/read/timing.rs
+++ b/crates/pptx/src/read/timing.rs
@@ -33,11 +33,11 @@ pub fn transition(imp: &mut Imp, part: &Part, t: &El) -> Option<Transition> {
         },
     }
     let default_dur = deckcraft_model::anim::TRANSITIONS.iter().find(|x| x.0 == tr.kind).map(|x| x.3).unwrap_or(1000);
+    // `spd` defaults to "fast" in the schema; PowerPoint omits both attributes for 0.5 s.
     tr.duration_ms = ms_attr(t, "dur").unwrap_or(match t.attr("spd") {
-        Some("fast") => 500,
         Some("med") => 750,
         Some("slow") => default_dur.max(1000),
-        _ => default_dur,
+        _ => 500,
     });
     if let Some(snd) = t.path(&["sndAc", "stSnd", "snd"]) {
         tr.sound = dml::media_ref(imp, part, snd);
diff --git a/crates/pptx/tests/transition_xml.rs b/crates/pptx/tests/transition_xml.rs
new file mode 100644
index 00000000..ffa5bcf4
--- /dev/null
+++ b/crates/pptx/tests/transition_xml.rs
@@ -0,0 +1,72 @@
+//! Transition XML as other applications write it, spliced into an exported deck and read back.
+
+use std::io::{Cursor, Read, Write};
+
+use deckcraft_model::anim::Transition;
+use deckcraft_model::defaults;
+
+const P159: &str = "http://schemas.microsoft.com/office/powerpoint/2015/09/main";
+const P14: &str = "http://schemas.microsoft.com/office/powerpoint/2010/main";
+
+/// Exports a one-slide deck, replaces the slide's `mc:AlternateContent` transition block with
+/// `xml` and returns the imported transition of that slide.
+fn import_with(xml: &str) -> Transition {
+    let mut p = defaults::new_presentation(None);
+    std::sync::Arc::make_mut(&mut p.slides[0]).transition = Some(Transition { kind: "fade".into(), duration_ms: 3000, ..Default::default() });
+    let bytes = deckcraft_pptx::export(&p).expect("export");
+    let mut z = zip::ZipArchive::new(Cursor::new(&bytes)).expect("zip");
+    let mut out = zip::ZipWriter::new(Cursor::new(Vec::new()));
+    let o = zip::write::SimpleFileOptions::default();
+    for i in 0..z.len() {
+        let mut f = z.by_index(i).expect("entry");
+        let mut d = vec![];
+        f.read_to_end(&mut d).expect("read");
+        if f.name() == "ppt/slides/slide1.xml" {
+            let s = String::from_utf8(d).expect("utf8");
+            let t = s.find("<p:transition").expect("transition");
+            let a = s[..t].rfind("<mc:AlternateContent").expect("mc start");
+            let end = "</mc:AlternateContent>";
+            let b = t + s[t..].find(end).expect("mc end") + end.len();
+            d = format!("{}{xml}{}", &s[..a], &s[b..]).into_bytes();
+        }
+        out.start_file(f.name(), o).expect("start");
+        out.write_all(&d).expect("write");
+    }
+    let bytes = out.finish().expect("finish").into_inner();
+    let q = deckcraft_pptx::import(&bytes).expect("import");
+    q.slides[0].transition.clone().expect("transition")
+}
+
+fn mc(choice_ns: &str, req: &str, choice: &str, fallback: &str) -> String {
+    format!(
+        r#"<mc:AlternateContent xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"><mc:Choice xmlns:{req}="{choice_ns}" Requires="{req}">{choice}</mc:Choice><mc:Fallback>{fallback}</mc:Fallback></mc:AlternateContent>"#
+    )
+}
+
+/// PowerPoint 2021/2024 write a 0.5 s Morph with neither `spd` nor `p14:dur` (issue #117).
+#[test]
+fn powerpoint_half_second_morph_without_spd() {
+    let xml = mc(P159, "p159", r#"<p:transition><p159:morph option="byObject"/></p:transition>"#, "<p:transition><p:fade/></p:transition>");
+    let t = import_with(&xml);
+    assert_eq!((t.kind.as_str(), t.duration_ms), ("morph", 500));
+}
+
+#[test]
+fn missing_spd_is_fast_for_a_plain_transition() {
+    let t = import_with("<p:transition><p:fade/></p:transition>");
+    assert_eq!((t.kind.as_str(), t.duration_ms), ("fade", 500));
+}
+
+#[test]
+fn spd_and_dur_still_apply() {
+    let t = import_with(r#"<p:transition spd="med"><p:fade/></p:transition>"#);
+    assert_eq!(t.duration_ms, 750);
+    let xml = mc(
+        P159,
+        "p159",
+        &format!(r#"<p:transition xmlns:p14="{P14}" spd="slow" p14:dur="1250"><p159:morph option="byObject"/></p:transition>"#),
+        r#"<p:transition spd="slow"><p:fade/></p:transition>"#,
+    );
+    let t = import_with(&xml);
+    assert_eq!((t.kind.as_str(), t.duration_ms), ("morph", 1250));
+}