diff --git a/crates/doc/src/setup.rs b/crates/doc/src/setup.rs
index ca08eca4a..4ab855329 100644
--- a/crates/doc/src/setup.rs
+++ b/crates/doc/src/setup.rs
@@ -308,9 +308,19 @@ impl DocSetup {
     pub fn keep_in_range(&mut self) {
         self.bleed = bleed_in_range(self.bleed);
         for m in [&mut self.superscript, &mut self.subscript] {
+            // `clamp` passes NaN through, so a non-finite value falls back to the default first.
+            if !m.size.is_finite() {
+                m.size = ScriptMetrics::DEFAULT.size;
+            }
+            if !m.position.is_finite() {
+                m.position = ScriptMetrics::DEFAULT.position;
+            }
             m.size = m.size.clamp(1.0, MAX_SCRIPT);
             m.position = m.position.clamp(-MAX_SCRIPT, MAX_SCRIPT);
         }
+        if !self.small_caps_size.is_finite() {
+            self.small_caps_size = DocSetup::default().small_caps_size;
+        }
         self.small_caps_size = self.small_caps_size.clamp(1.0, MAX_SMALL_CAPS);
     }
 }
@@ -353,6 +363,20 @@ mod tests {
         assert!(s.has_bleed() && !DocSetup::default().has_bleed());
     }
 
+    #[test]
+    fn keep_in_range_replaces_non_finite_type_values() {
+        let mut s = DocSetup::default();
+        s.superscript.size = f64::NAN;
+        s.superscript.position = f64::INFINITY;
+        s.subscript.size = f64::NEG_INFINITY;
+        s.subscript.position = f64::NAN;
+        s.small_caps_size = f64::NAN;
+        s.keep_in_range();
+        for v in [s.superscript.size, s.superscript.position, s.subscript.size, s.subscript.position, s.small_caps_size] {
+            assert!(v.is_finite(), "{v}");
+        }
+    }
+
     #[test]
     fn presets_and_defaults() {
         let d = DocSetup::default();