diff --git a/lib/dns/rdata/generic/l32_105.c b/lib/dns/rdata/generic/l32_105.c
index 9657711bb8..5f2d8933bb 100644
--- a/lib/dns/rdata/generic/l32_105.c
+++ b/lib/dns/rdata/generic/l32_105.c
@@ -156,6 +156,8 @@ tostruct_l32(ARGS_TOSTRUCT) {
 
 	dns_rdata_toregion(rdata, &region);
 	l32->pref = uint16_fromregion(&region);
+	isc_region_consume(&region, 2);
+	INSIST(region.length == sizeof(l32->l32));
 	n = uint32_fromregion(&region);
 	l32->l32.s_addr = htonl(n);
 	return ISC_R_SUCCESS;
diff --git a/lib/dns/rdata/generic/l64_106.c b/lib/dns/rdata/generic/l64_106.c
index 5e9b42e451..493264fa55 100644
--- a/lib/dns/rdata/generic/l64_106.c
+++ b/lib/dns/rdata/generic/l64_106.c
@@ -151,6 +151,8 @@ tostruct_l64(ARGS_TOSTRUCT) {
 
 	dns_rdata_toregion(rdata, &region);
 	l64->pref = uint16_fromregion(&region);
+	isc_region_consume(&region, 2);
+	INSIST(region.length == sizeof(l64->l64));
 	memmove(l64->l64, region.base, region.length);
 	return ISC_R_SUCCESS;
 }
diff --git a/lib/dns/rdata/generic/nid_104.c b/lib/dns/rdata/generic/nid_104.c
index 80d0533057..275772b9e4 100644
--- a/lib/dns/rdata/generic/nid_104.c
+++ b/lib/dns/rdata/generic/nid_104.c
@@ -151,6 +151,8 @@ tostruct_nid(ARGS_TOSTRUCT) {
 
 	dns_rdata_toregion(rdata, &region);
 	nid->pref = uint16_fromregion(&region);
+	isc_region_consume(&region, 2);
+	INSIST(region.length == sizeof(nid->nid));
 	memmove(nid->nid, region.base, region.length);
 	return ISC_R_SUCCESS;
 }