diff --git a/lib/std/array_hash_map.zig b/lib/std/array_hash_map.zig
index 470150ad6b..4e18aecf9d 100644
--- a/lib/std/array_hash_map.zig
+++ b/lib/std/array_hash_map.zig
@@ -80,8 +80,10 @@ pub fn ArrayHashMapWithAllocator(
     comptime V: type,
     /// A namespace that provides these two functions:
     /// * `pub fn hash(self, K) u32`
-    /// * `pub fn eql(self, K, K) bool`
+    /// * `pub fn eql(self, K, K, usize) bool`
     ///
+    /// The final `usize` in the `eql` function represents the index of the key
+    /// that's already inside the map.
     comptime Context: type,
     /// When `false`, this data structure is biased towards cheap `eql`
     /// functions and avoids storing each key's hash in the table. Setting
@@ -525,7 +527,10 @@ pub fn ArrayHashMapUnmanaged(
     comptime V: type,
     /// A namespace that provides these two functions:
     /// * `pub fn hash(self, K) u32`
-    /// * `pub fn eql(self, K, K) bool`
+    /// * `pub fn eql(self, K, K, usize) bool`
+    ///
+    /// The final `usize` in the `eql` function represents the index of the key
+    /// that's already inside the map.
     comptime Context: type,
     /// When `false`, this data structure is biased towards cheap `eql`
     /// functions and avoids storing each key's hash in the table. Setting