diff --git a/wgengine/magicsock/magicsock.go b/wgengine/magicsock/magicsock.go
index ed0a71b0e..06fd5e59b 100644
--- a/wgengine/magicsock/magicsock.go
+++ b/wgengine/magicsock/magicsock.go
@@ -1952,6 +1952,8 @@ type connBind struct {
 	closed bool
 }
 
+// This is a compile-time assertion that connBind implements the wireguard-go
+// conn.Bind interface.
 var _ conn.Bind = (*connBind)(nil)
 
 // BatchSize returns the number of buffers expected to be passed to