diff --git a/crates/textimport/src/docx.rs b/crates/textimport/src/docx.rs
index 4d90a6b7..87aaa335 100644
--- a/crates/textimport/src/docx.rs
+++ b/crates/textimport/src/docx.rs
@@ -186,8 +186,9 @@ fn run_attrs(rpr: Option<&El>) -> CharAttrs {
     if let Some(s) = r.on("strike") {
         a.strikethrough = Some(s);
     }
-    if let Some(sz) = r.val("sz").and_then(|v| v.parse::<f64>().ok()).filter(|v| v.is_finite()) {
-        a.size = Some(sz / 2.0);
+    // Half-points; sizes outside the engine's 0.1–1296 pt range (or non-finite) are dropped.
+    if let Some(pt) = r.val("sz").and_then(|v| v.parse::<f64>().ok()).map(|sz| sz / 2.0).filter(|pt| (0.1..=1296.0).contains(pt)) {
+        a.size = Some(pt);
     }
     if let Some(f) = r.child("rFonts").and_then(|f| f.attr("ascii").or(f.attr("hAnsi"))) {
         a.font_family = Some(f.to_string());
@@ -714,6 +715,19 @@ mod tests {
         }
     }
 
+    #[test]
+    fn out_of_range_sizes_are_dropped() {
+        let document = format!(
+            r#"<w:document {W}><w:body>
+              <w:p><w:r><w:rPr><w:sz w:val="0"/></w:rPr><w:t>a</w:t></w:r><w:r><w:rPr><w:sz w:val="99999999"/></w:rPr><w:t>b</w:t></w:r></w:p>
+            </w:body></w:document>"#
+        );
+        let st = import(&docx(&document, "", "")).unwrap().story;
+        for at in [0, 1] {
+            assert_eq!(st.format_after(at).over.size, None, "run {at}");
+        }
+    }
+
     #[test]
     fn tracked_changes_import_as_accepted_including_moves() {
         // Regression (#256): text in a tracked move destination (`w:moveTo`) vanished on import.