diff --git a/pkg/registry/core/service/ipallocator/ipallocator.go b/pkg/registry/core/service/ipallocator/ipallocator.go
index 8618d541aff..d407ddf5fda 100644
--- a/pkg/registry/core/service/ipallocator/ipallocator.go
+++ b/pkg/registry/core/service/ipallocator/ipallocator.go
@@ -484,11 +484,21 @@ func (dry dryRunAllocator) EnableMetrics() {
 // TODO: move it to k8s.io/utils/net, this is the same as current AddIPOffset()
 // but using netip.Addr instead of net.IP
 func addOffsetAddress(address netip.Addr, offset uint64) (netip.Addr, error) {
-	addressBig := big.NewInt(0).SetBytes(address.AsSlice())
-	r := big.NewInt(0).Add(addressBig, big.NewInt(int64(offset)))
-	addr, ok := netip.AddrFromSlice(r.Bytes())
+	addressBytes := address.AsSlice()
+	addressBig := big.NewInt(0).SetBytes(addressBytes)
+	r := big.NewInt(0).Add(addressBig, big.NewInt(int64(offset))).Bytes()
+	// r must be 4 or 16 bytes depending of the ip family
+	// bigInt conversion to bytes will not take this into consideration
+	// and drop the leading zeros, so we have to take this into account.
+	lenDiff := len(addressBytes) - len(r)
+	if lenDiff > 0 {
+		r = append(make([]byte, lenDiff), r...)
+	} else if lenDiff < 0 {
+		return netip.Addr{}, fmt.Errorf("invalid address %v", r)
+	}
+	addr, ok := netip.AddrFromSlice(r)
 	if !ok {
-		return netip.Addr{}, fmt.Errorf("invalid address %v", r.Bytes())
+		return netip.Addr{}, fmt.Errorf("invalid address %v", r)
 	}
 	return addr, nil
 }
diff --git a/pkg/registry/core/service/ipallocator/ipallocator_test.go b/pkg/registry/core/service/ipallocator/ipallocator_test.go
index 5e80115278a..6c5c73cde76 100644
--- a/pkg/registry/core/service/ipallocator/ipallocator_test.go
+++ b/pkg/registry/core/service/ipallocator/ipallocator_test.go
@@ -587,6 +587,18 @@ func Test_addOffsetAddress(t *testing.T) {
 			offset:  128,
 			want:    netip.MustParseAddr("192.168.0.128"),
 		},
+		{
+			name:    "IPv4 with leading zeros",
+			address: netip.MustParseAddr("0.0.1.8"),
+			offset:  138,
+			want:    netip.MustParseAddr("0.0.1.146"),
+		},
+		{
+			name:    "IPv6 with leading zeros",
+			address: netip.MustParseAddr("00fc::1"),
+			offset:  255,
+			want:    netip.MustParseAddr("fc::100"),
+		},
 		{
 			name:    "IPv6 offset 255",
 			address: netip.MustParseAddr("2001:db8:1::101"),
@@ -643,6 +655,16 @@ func Test_broadcastAddress(t *testing.T) {
 			subnet: netip.MustParsePrefix("fd00:1:2:3::/64"),
 			want:   netip.MustParseAddr("fd00:1:2:3:FFFF:FFFF:FFFF:FFFF"),
 		},
+		{
+			name:   "ipv6 00fc::/112",
+			subnet: netip.MustParsePrefix("00fc::/112"),
+			want:   netip.MustParseAddr("fc::ffff"),
+		},
+		{
+			name:   "ipv6 fc00::/112",
+			subnet: netip.MustParsePrefix("fc00::/112"),
+			want:   netip.MustParseAddr("fc00::ffff"),
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -888,6 +910,25 @@ func Test_ipIterator_Number(t *testing.T) {
 	}
 }
 
+func TestAllocateNextFC(t *testing.T) {
+	_, cidr, err := netutils.ParseCIDRSloppy("fc::/112")
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Logf("CIDR %s", cidr)
+
+	r, err := newTestAllocator(cidr)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer r.Destroy()
+	ip, err := r.AllocateNext()
+	if err != nil {
+		t.Fatalf("wrong ip %s : %v", ip, err)
+	}
+	t.Log(ip.String())
+}
+
 func BenchmarkIPAllocatorAllocateNextIPv4Size1048574(b *testing.B) {
 	_, cidr, err := netutils.ParseCIDRSloppy("10.0.0.0/12")
 	if err != nil {