diff --git a/src/autoload.rs b/src/autoload.rs
index ce1981261..78e51429b 100644
--- a/src/autoload.rs
+++ b/src/autoload.rs
@@ -212,7 +212,7 @@ pub fn clear(&mut self) {
     /// This is exposed for testing.
     #[cfg(test)]
     fn invalidate_cache(&mut self) {
-        self.cache = Box::new(AutoloadFileCache::with_dirs(self.cache.dirs().to_owned()));
+        *self.cache = AutoloadFileCache::with_dirs(self.cache.dirs().to_owned());
     }
 
     /// Like resolve_autoload(), but accepts the paths directly.
@@ -227,7 +227,7 @@ fn resolve_command_impl(&mut self, cmd: &wstr, paths: &[WString]) -> AutoloadRes
         // Note we don't have to modify autoloadable_files_. We'll naturally detect if those have
         // changed when we query the cache.
         if paths != self.cache.dirs() {
-            self.cache = Box::new(AutoloadFileCache::with_dirs(paths.to_owned()));
+            *self.cache = AutoloadFileCache::with_dirs(paths.to_owned());
         }
 
         // Do we have an entry to load?
diff --git a/src/builtins/block.rs b/src/builtins/block.rs
index 2b7713031..4fcb2fcbd 100644
--- a/src/builtins/block.rs
+++ b/src/builtins/block.rs
@@ -3,19 +3,14 @@
 // Implementation of the block builtin.
 use super::prelude::*;
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
 enum Scope {
+    #[default]
     Unset,
     Global,
     Local,
 }
 
-impl Default for Scope {
-    fn default() -> Self {
-        Self::Unset
-    }
-}
-
 #[derive(Debug, Clone, Copy, Default)]
 struct Options {
     scope: Scope,
diff --git a/src/highlight/highlight.rs b/src/highlight/highlight.rs
index f1cb3090a..3efb19994 100644
--- a/src/highlight/highlight.rs
+++ b/src/highlight/highlight.rs
@@ -1212,17 +1212,13 @@ fn get_fallback(role: HighlightRole) -> HighlightRole {
     }
 }
 
-impl Default for HighlightRole {
-    fn default() -> Self {
-        Self::normal
-    }
-}
-
 /// Describes the role of a span of text.
 #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
 #[repr(u8)]
+#[derive(Default)]
 pub enum HighlightRole {
-    normal,  // normal text
+    #[default]
+    normal, // normal text
     error,   // error
     command, // command
     keyword,