diff --git a/types/params.go b/types/params.go
index f0d8714f8..3540805cc 100644
--- a/types/params.go
+++ b/types/params.go
@@ -77,7 +77,9 @@ type VersionParams struct {
 }
 
 // SynchronyParams influence the validity of block timestamps.
-// TODO (@wbanfield): add link to proposer-based timestamp spec when completed.
+// For more information on the relationship of the synchrony parameters to
+// block validity, see the Proposer-Based Timestamps specification:
+// https://github.com/tendermint/spec/blob/master/spec/consensus/proposer-based-timestamp/README.md
 type SynchronyParams struct {
 	Precision    time.Duration `json:"precision,string"`
 	MessageDelay time.Duration `json:"message_delay,string"`