diff --git a/crates/aep/src/container/effect_map.rs b/crates/aep/src/container/effect_map.rs
index 06b80cc3a..49a53d2e7 100644
--- a/crates/aep/src/container/effect_map.rs
+++ b/crates/aep/src/container/effect_map.rs
@@ -1142,8 +1142,12 @@ pub const GLOW_MIDPOINT_MAX: f64 = 0.990_005_493_164_062_5;
 
 /// The key a popup item is matched by between the two programs: trimmed, lower case, and
 /// Set Matte's "Red Channel" ... "Alpha Channel" are EffectCraft's "Red" ... "Alpha" (904 E24).
+///
+/// Lower case is Unicode's, not only ASCII's: After Effects stores popup items in its UI
+/// language, so an item can start with a capital outside ASCII (French "Écran"), and its key must
+/// be the same as for the same word in lower case.
 pub fn popup_key(item: &str) -> String {
-    let s = item.trim().to_ascii_lowercase();
+    let s = item.trim().to_lowercase();
     s.strip_suffix(" channel").map(str::to_string).unwrap_or(s)
 }
 
@@ -1186,3 +1190,17 @@ pub const HUE_SATURATION_MASTER: [&str; 3] = ["hue", "saturation", "lightness"];
 /// The EffectCraft parameters Levels' RGB channel values (`Extra::Levels`) go to, in the order of
 /// the data (input black, input white, gamma, output black, output white: 512-516).
 pub const LEVELS_RGB: [&str; 5] = ["inBlack", "inWhite", "gamma", "outBlack", "outWhite"];
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// A capital outside ASCII has the same key as its lower case; ASCII keys are unchanged.
+    #[test]
+    fn popup_key_lowers_non_ascii_capitals() {
+        assert_eq!(popup_key("ÉCRAN"), popup_key("écran"));
+        assert_eq!(popup_key(" Désactivé "), "désactivé");
+        assert_eq!(popup_key("Off for 32 bpc Color"), "off for 32 bpc color");
+        assert_eq!(popup_key("Red Channel"), "red");
+    }
+}