diff --git a/CHANGELOG.md b/CHANGELOG.md
index 08b625d20..87ce81a2f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,8 @@ FEATURES:
 
 IMPROVEMENTS:
 
+* core: builders can now give warnings during validation. warnings won't
+  fail the build but may hint at potential future problems.
 * builder/vmware,builder/virtualbox: ISO urls can now be https [GH-587]
 * builder/virtualbox: Can now disable guest addition download entirely
   by setting "guest_additions_mode" to "disable" [GH-580]