diff --git a/src/maps/maps.go b/src/maps/maps.go
index c92106710d..b712dd3fe8 100644
--- a/src/maps/maps.go
+++ b/src/maps/maps.go
@@ -3,6 +3,9 @@
 // license that can be found in the LICENSE file.
 
 // Package maps defines various functions useful with maps of any type.
+//
+// This package does not have any special handling for non-reflexive keys
+// (keys k where k != k), such as floating-point NaNs.
 package maps
 
 import (