diff --git a/docs/changelog.rst b/docs/changelog.rst
index 6498e7c..a5e2fb1 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -29,6 +29,14 @@ We use the following annotations for classifying changes:
 This release is a milestone for zrepl and required significant refactoring if not rewrites of substantial parts of the application.
 It breaks both configuration and transport format, and thus requires manual intervention and updates on both sides of a replication setup.
 
+.. DANGER::
+   The changes in the pruning system for this release require you to explicitly define **keep rules**:
+   for any snapshot that you want to keep, at least one rule must match.
+   This is different from previous releases where pruning only affected snapshots with the configured snapshotting prefix.
+   Make sure that snapshots to be kept or ignored by zrepl are covered, e.g. by using the ``regex`` keep rule.
+   :ref:`Learn more in the config docs... <prune>`
+
+
 Notes to Package Maintainers
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/docs/configuration/prune.rst b/docs/configuration/prune.rst
index 7aaacad..f0e80b6 100644
--- a/docs/configuration/prune.rst
+++ b/docs/configuration/prune.rst
@@ -45,6 +45,9 @@ Example Configuration:
              regex: "^zrepl_.*"
            # manually created snapshots will be kept forever on receiver
 
+.. DANGER::
+    You might have **existing snapshots** of filesystems affected by pruning which you want to keep, i.e. not be destroyed by zrepl.
+    Make sure to actually add the necessary ``regex`` keep rules on both sides, like with ``manual`` in the example above.
 
 .. ATTENTION::