diff --git a/db/model/branch.go b/db/model/branch.go
index 2066643..675c45d 100644
--- a/db/model/branch.go
+++ b/db/model/branch.go
@@ -166,7 +166,5 @@
 	b.mutex.Lock()
 	defer b.mutex.Unlock()
 
-	if _, ok := b.Revisions[hash]; ok {
-		delete(b.Revisions, hash)
-	}
+	delete(b.Revisions, hash)
 }
diff --git a/db/model/model.go b/db/model/model.go
index 4c944bf..f80f957 100644
--- a/db/model/model.go
+++ b/db/model/model.go
@@ -26,13 +26,15 @@
 	}
 }
 
+type contextKey string
+
 const (
 	// DataRefreshPeriod is period to determine when data requires a refresh (in milliseconds)
 	// TODO: make this configurable?
 	DataRefreshPeriod int64 = 5000
 
 	// RequestTimestamp attribute used to store a timestamp in the context object
-	RequestTimestamp = "request-timestamp"
+	RequestTimestamp contextKey = "request-timestamp"
 
 	// ReservationTTL is time limit for a KV path reservation (in seconds)
 	ReservationTTL int64 = 180