diff --git a/wireguard.go b/wireguard.go
index bd4b7b7..b464d5f 100644
--- a/wireguard.go
+++ b/wireguard.go
@@ -58,7 +58,7 @@ func newWGConfig(iface string, port int) (*wgState, error) {
 func (wg *wgState) assignOverlayAddr(ipnet *net.IPNet, name string) {
 	// TODO: this is way too brittle and opaque
 	bits, size := ipnet.Mask.Size()
-	ip := make([]byte, net.IPv6len)
+	ip := make([]byte, len(ipnet.IP))
 	copy(ip, []byte(ipnet.IP))
 
 	h := fnv.New128a()
diff --git a/wireguard_test.go b/wireguard_test.go
index 6f672b1..95ac0ca 100644
--- a/wireguard_test.go
+++ b/wireguard_test.go
@@ -43,20 +43,22 @@ func Test_wgState_assignOverlayAddr(t *testing.T) {
 		ipnet *net.IPNet
 		name  string
 	}
+	_, ipv4net, _ := net.ParseCIDR("10.0.0.0/8")
+	_, ipv6net, _ := net.ParseCIDR("2001:db8::/32")
 	tests := []struct {
 		name string
 		args args
-		want net.IP
+		want string
 	}{
 		{
 			"assign in big ipv4 net",
-			args{&net.IPNet{IP: net.ParseIP("10.0.0.0"), Mask: net.CIDRMask(8, 32)}, "test"},
-			net.ParseIP("10.221.153.165"), // if we ever have to change this, we should probably also mark it as a breaking change
+			args{ipv4net, "test"},
+			"10.221.153.165", // if we ever have to change this, we should probably also mark it as a breaking change
 		},
 		{
 			"assign in ipv6 net",
-			args{&net.IPNet{IP: net.ParseIP("2001:db8::"), Mask: net.CIDRMask(32, 128)}, "test"},
-			net.ParseIP("2001:db8:c575:7277:b806:e994:13dd:99a5"), // if we ever have to change this, we should probably also mark it as a breaking change
+			args{ipv6net, "test"},
+			"2001:db8:c575:7277:b806:e994:13dd:99a5", // if we ever have to change this, we should probably also mark it as a breaking change
 		},
 	}
 	for _, tt := range tests {
@@ -64,7 +66,7 @@ func Test_wgState_assignOverlayAddr(t *testing.T) {
 			wg := &wgState{}
 			wg.assignOverlayAddr(tt.args.ipnet, tt.args.name)
 
-			if !reflect.DeepEqual(wg.OverlayAddr, tt.want) {
+			if !reflect.DeepEqual(wg.OverlayAddr.String(), tt.want) {
 				t.Errorf("assignOverlayAddr() set = %s, want %s", wg.OverlayAddr, tt.want)
 			}
 		})
@@ -74,7 +76,7 @@ func Test_wgState_assignOverlayAddr(t *testing.T) {
 // This is just to ensure - if we ever change the hashing function - that it spreads the results in a way that at least
 // avoids the most obvious collisions.
 func Test_wgState_assignOverlayAddr_no_obvious_collisions(t *testing.T) {
-	ipnet := &net.IPNet{IP: net.ParseIP("10.0.0.0"), Mask: net.CIDRMask(24, 32)}
+	_, ipnet, _ := net.ParseCIDR("10.0.0.0/24")
 	assignments := make(map[string]string)
 	for _, n := range []string{"test", "test1", "test2", "1test", "2test"} {
 		wg := &wgState{}
@@ -87,8 +89,8 @@ func Test_wgState_assignOverlayAddr_no_obvious_collisions(t *testing.T) {
 }
 
 // This should ensure the obvious fact that the same name should map to the same IP if called twice.
-func Test_wgState_assignOverlayAddr_repeatable(t *testing.T) {
-	ipnet := &net.IPNet{IP: net.ParseIP("10.0.0.0"), Mask: net.CIDRMask(24, 32)}
+func Test_wgState_assignOverlayAddr_consistent(t *testing.T) {
+	_, ipnet, _ := net.ParseCIDR("10.0.0.0/8")
 	wg1 := &wgState{}
 	wg1.assignOverlayAddr(ipnet, "test")
 	wg2 := &wgState{}
@@ -97,3 +99,15 @@ func Test_wgState_assignOverlayAddr_repeatable(t *testing.T) {
 		t.Errorf("assignOverlayAddr() %s != %s", wg1.OverlayAddr, wg2.OverlayAddr)
 	}
 }
+
+func Test_wgState_assignOverlayAddr_repeatable(t *testing.T) {
+	_, ipnet, _ := net.ParseCIDR("10.0.0.0/8")
+	wg := &wgState{}
+	wg.assignOverlayAddr(ipnet, "test")
+	gen1 := wg.OverlayAddr.String()
+	wg.assignOverlayAddr(ipnet, "test")
+	gen2 := wg.OverlayAddr.String()
+	if gen1 != gen2 {
+		t.Errorf("assignOverlayAddr() %s != %s", gen1, gen2)
+	}
+}