diff --git a/crates/egui/src/memory/mod.rs b/crates/egui/src/memory/mod.rs
index 3a6053f7..d38e39f7 100644
--- a/crates/egui/src/memory/mod.rs
+++ b/crates/egui/src/memory/mod.rs
@@ -322,7 +322,7 @@ impl Default for Options {
         Self {
             dark_style: std::sync::Arc::new(Theme::Dark.default_style()),
             light_style: std::sync::Arc::new(Theme::Light.default_style()),
-            theme_preference: ThemePreference::System,
+            theme_preference: Default::default(),
             fallback_theme: Theme::Dark,
             system_theme: None,
             zoom_factor: 1.0,
diff --git a/crates/egui/src/memory/theme.rs b/crates/egui/src/memory/theme.rs
index 6d027b3b..4a63ecd5 100644
--- a/crates/egui/src/memory/theme.rs
+++ b/crates/egui/src/memory/theme.rs
@@ -66,7 +66,7 @@ impl Theme {
 }
 
 /// The user's theme preference.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+#[derive(Debug, Default, Clone, Copy, PartialEq, Eq, Hash)]
 #[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
 pub enum ThemePreference {
     /// Dark mode: light text on a dark background.
@@ -76,6 +76,7 @@ pub enum ThemePreference {
     Light,
 
     /// Follow the system's theme preference.
+    #[default]
     System,
 }