diff --git a/doc/api/dns.md b/doc/api/dns.md
index 45d494eab3bcf2..329ff0c3ae028a 100644
--- a/doc/api/dns.md
+++ b/doc/api/dns.md
@@ -323,7 +323,7 @@ Uses the DNS protocol to resolve name server records (`NS` records) for the
 contain an array of name server records available for `hostname`
 (e.g. `['ns1.example.com', 'ns2.example.com']`).
 
-## dns.resolvePtr(hostname)
+## dns.resolvePtr(hostname, callback)
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