diff --git a/apps/overlays/au-syd1/externaldns/values.yaml b/apps/overlays/au-syd1/externaldns/values.yaml
index 865aa0c..e1d4281 100644
--- a/apps/overlays/au-syd1/externaldns/values.yaml
+++ b/apps/overlays/au-syd1/externaldns/values.yaml
@@ -51,7 +51,7 @@ extraArgs:
   # Synthesize PTR records into the reverse zone for every A record managed in
   # the forward zone (the reverse zone + resolver forwarder exist since #288;
   # without this flag nothing writes PTRs).
-  - --rfc2136-create-ptr
+  - --create-ptr
   - --rfc2136-tsig-keyname=externaldns-key
   - --rfc2136-tsig-secret-alg=$(EXTERNAL_DNS_RFC2136_TSIG_ALGORITHM)
   - --rfc2136-tsig-axfr