diff --git a/drafts/str4d-overwinter-activation/draft1.rst b/drafts/str4d-overwinter-activation/draft1.rst
index 9f18aaff..da02e9c6 100644
--- a/drafts/str4d-overwinter-activation/draft1.rst
+++ b/drafts/str4d-overwinter-activation/draft1.rst
@@ -167,7 +167,7 @@ While the current chain tip height is below ``ACTIVATION_HEIGHT``, nodes SHOULD
 will only be valid on the post-upgrade branch.
 
 When the current chain tip height reaches ``ACTIVATION_HEIGHT``, the node's local transaction memory pool
-SHOULD be cleared.
+SHOULD be cleared of transactions that will never be valid on the post-upgrade branch.
 
 Two-way replay protection
 -------------------------