diff --git a/lib/dns/rdata/in_1/apl_42.c b/lib/dns/rdata/in_1/apl_42.c
index ee33fa5c57..ba0d3d041b 100644
--- a/lib/dns/rdata/in_1/apl_42.c
+++ b/lib/dns/rdata/in_1/apl_42.c
@@ -331,6 +331,8 @@ dns_rdata_apl_first(dns_rdata_in_apl_t *apl) {
 		return ISC_R_NOMORE;
 	}
 
+	apl->offset = 0;
+
 	/*
 	 * Sanity check data.
 	 */
@@ -338,7 +340,6 @@ dns_rdata_apl_first(dns_rdata_in_apl_t *apl) {
 	length = apl->apl[apl->offset + 3] & 0x7f;
 	INSIST(4 + length <= apl->apl_len);
 
-	apl->offset = 0;
 	return ISC_R_SUCCESS;
 }