diff --git a/compiler/rustc_expand/src/base.rs b/compiler/rustc_expand/src/base.rs
index c47c076e56ef..205aa47c1a02 100644
--- a/compiler/rustc_expand/src/base.rs
+++ b/compiler/rustc_expand/src/base.rs
@@ -776,6 +776,8 @@ pub enum SyntaxExtensionKind {
     ),
 
     /// A glob delegation.
+    ///
+    /// This is for delegated function implementations, and has nothing to do with glob imports.
     GlobDelegation(Arc<dyn GlobDelegationExpander + sync::DynSync + sync::DynSend>),
 }