diff --git a/internal/dnsfilter/safebrowsing_test.go b/internal/dnsfilter/safebrowsing_test.go
index a9390f4b8e6..68f76a241f6 100644
--- a/internal/dnsfilter/safebrowsing_test.go
+++ b/internal/dnsfilter/safebrowsing_test.go
@@ -144,7 +144,7 @@ type testSbUpstream struct {
 	requestsCount int
 }
 
-// Exchange always returns a message with random hashes
+// Exchange always returns a message with random hashes.
 func (u *testSbUpstream) Exchange(r *dns.Msg) (*dns.Msg, error) {
 	u.requestsCount++