diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6d9c07acd..3751829d1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@ BACKWARDS INCOMPATIBILITIES / NOTES:
 NEW FEATURES:
 
 * **Local Values**: this new configuration language feature allows assigning a symbolic local name to an expression so it can be used multiple times in configuration without repetition. See [the documentation](https://github.com/hashicorp/terraform/blob/master/website/docs/configuration/locals.html.md) for how to define and use local values. [GH-15449]
+* **`base64gzip` interpolation function**: compresses a string with gzip and then base64-encodes the result [GH-3858]
 * **`flatten` interpolation function**: turns a list of lists, or list of lists of lists, etc into a flat list of primitive values [GH-15278]
 
 IMPROVEMENTS: