diff --git a/e2e/wildcard_test.go b/e2e/wildcard_test.go
new file mode 100644
index 0000000..2882e97
--- /dev/null
+++ b/e2e/wildcard_test.go
@@ -0,0 +1,66 @@
+package e2e
+
+import (
+	"context"
+	"encoding/json"
+	"io"
+	"net"
+	"net/http"
+	"strconv"
+	"testing"
+	"time"
+
+	"git.veillax.com/Veillax/blacktip"
+	"git.veillax.com/Veillax/reef/model"
+)
+
+// A website on every address does not take the port from a website that names an address: each
+// listens where it should, and the named address answers only for its own site.
+func TestWildcardWebsiteStepsAsideForANamedAddress(t *testing.T) {
+	w := setup(t, blacktip.TraefikConfig{})
+	w.admin.must("POST", "/api/orgs/"+w.org+"/domains", map[string]any{"name": "example.test", "edgeId": w.edge}, nil)
+	wild, named := webBackend(t, "wild", 200), webBackend(t, "named", 200)
+	port := freePort(t)
+
+	w.open(model.Mapping{Proto: "http", BindIP: "0.0.0.0", Port: port, Hostname: "wild.example.test", Targets: tgt(w.site, wild)})
+	w.open(model.Mapping{Proto: "http", BindIP: "127.0.0.2", Port: port, Hostname: "named.example.test", Targets: tgt(w.site, named)})
+
+	ask := func(ip, host string) (int, string) {
+		c := &http.Client{Timeout: 3 * time.Second, Transport: &http.Transport{DisableKeepAlives: true,
+			DialContext: func(ctx context.Context, _, _ string) (net.Conn, error) {
+				return (&net.Dialer{}).DialContext(ctx, "tcp", net.JoinHostPort(ip, strconv.Itoa(port)))
+			}}}
+		req, _ := http.NewRequest("GET", "http://"+host+"/", nil)
+		resp, err := c.Do(req)
+		if err != nil {
+			return 0, err.Error()
+		}
+		defer resp.Body.Close()
+		b, _ := io.ReadAll(resp.Body)
+		var body map[string]string
+		json.Unmarshal(b, &body)
+		return resp.StatusCode, body["backend"]
+	}
+	wait := func(ip, host, wantBackend string) {
+		t.Helper()
+		var code int
+		var got string
+		for i := 0; i < 60; i++ {
+			if code, got = ask(ip, host); code == 200 && got == wantBackend {
+				return
+			}
+			time.Sleep(150 * time.Millisecond)
+		}
+		t.Fatalf("%s via %s: status %d backend %q, want %q", host, ip, code, got, wantBackend)
+	}
+
+	wait("127.0.0.2", "named.example.test", "named") // the named address serves its own site
+	wait("127.0.0.1", "wild.example.test", "wild")   // the wildcard still covers the other addresses
+	// and the wildcard gave up the named address: its site is not served there
+	if code, _ := ask("127.0.0.2", "wild.example.test"); code == 200 {
+		t.Errorf("the wildcard website still answers on the address another website names")
+	}
+	if code, _ := ask("127.0.0.1", "named.example.test"); code == 200 {
+		t.Errorf("a website answers on an address it was not given")
+	}
+}
diff --git a/mappings.go b/mappings.go
index e5a24f2..1270e49 100644
--- a/mappings.go
+++ b/mappings.go
@@ -204,8 +204,24 @@ func (s *Server) validateMapping(c *orgCtx, m *model.Mapping) error {
 		if m.Proto == o.Proto && model.HostBased(m.Proto) && m.BindIP == o.BindIP && m.Hostname != o.Hostname {
 			continue // same listener, different hostname
 		}
+		if m.Proto == o.Proto && model.Web(m.Proto) && m.BindIP != o.BindIP && isWild(m.BindIP) != isWild(o.BindIP) {
+			continue // a website on every address steps aside for one that names an address
+		}
 		return fmt.Errorf("%s port %s on %s is already used by %q. Choose another port or address.", strings.ToUpper(netClass(m.Proto)), portLabel(*m), o.BindIP, o.Name)
 	}
+	// an https resource with the redirect on also answers on port 80 at its address, so a raw port
+	// there would clash with it (and the other way round)
+	for _, o := range s.st.Mappings {
+		if o.ID == m.ID || o.EdgeID != m.EdgeID || !overlap(o.BindIP, m.BindIP) {
+			continue
+		}
+		switch {
+		case m.Proto == model.ProtoHTTPS && m.RedirectHTTP && netClass(o.Proto) == "tcp" && !model.Web(o.Proto) && o.Port <= 80 && 80 <= o.LastPort():
+			return fmt.Errorf("Redirecting HTTP to HTTPS also uses TCP port 80 on %s, which %q uses. Turn the redirect off or choose another port for %q.", o.BindIP, o.Name, o.Name)
+		case o.Proto == model.ProtoHTTPS && o.RedirectHTTP && netClass(m.Proto) == "tcp" && !model.Web(m.Proto) && m.Port <= 80 && 80 <= m.LastPort():
+			return fmt.Errorf("TCP port 80 on %s is also used by %q to redirect HTTP to HTTPS. Choose another port, or turn that redirect off.", o.BindIP, o.Name)
+		}
+	}
 	if m.Name == "" {
 		if m.Hostname != "" {
 			m.Name = m.Hostname
diff --git a/mappings_test.go b/mappings_test.go
new file mode 100644
index 0000000..b0ed9d7
--- /dev/null
+++ b/mappings_test.go
@@ -0,0 +1,76 @@
+package hammerhead
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+)
+
+// websites share a port by hostname, and a website on every address steps aside for one that names an address
+func TestWebsitesShareAPortAndWildcardsStepAside(t *testing.T) {
+	s, err := New(t.TempDir(), Options{AdminEmail: "admin@test.local", AdminPassword: "password123", MasterKey: key})
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer s.Close()
+	do := apiClient(t, s)
+	var me struct{ Orgs []struct{ ID string } }
+	_, b := do("GET", "/api/me", nil)
+	json.Unmarshal(b, &me)
+	org := me.Orgs[0].ID
+	var edge, site struct{ ID string }
+	_, b = do("POST", "/api/edges", map[string]any{"name": "e", "tunnelAddr": "203.0.113.5:51820"})
+	json.Unmarshal(b, &edge)
+	_, b = do("POST", "/api/orgs/"+org+"/sites", map[string]any{"name": "home"})
+	json.Unmarshal(b, &site)
+	if code, b := do("POST", "/api/orgs/"+org+"/domains", map[string]any{"name": "example.test", "edgeId": edge.ID, "ip": "203.0.113.10"}); code != 200 {
+		t.Fatalf("domain: %d %s", code, b)
+	}
+	base := "/api/orgs/" + org + "/mappings"
+	open := func(m map[string]any) (int, string) {
+		m["edgeId"] = edge.ID
+		m["enabled"] = true
+		m["targets"] = []any{map[string]any{"siteId": site.ID, "host": "127.0.0.1", "port": 8080}}
+		code, b := do("POST", base, m)
+		return code, string(b)
+	}
+	want := func(code int, got int, body, what string) {
+		t.Helper()
+		if code != got {
+			t.Errorf("%s: got %d, want %d (%s)", what, got, code, body)
+		}
+	}
+
+	c, body := open(map[string]any{"proto": "https", "bindIp": "0.0.0.0", "port": 443, "hostname": "a.example.test"})
+	want(200, c, body, "first website on every address")
+	c, body = open(map[string]any{"proto": "https", "bindIp": "203.0.113.10", "port": 443, "hostname": "b.example.test"})
+	want(200, c, body, "a website naming an address shares the port with the wildcard one")
+	c, body = open(map[string]any{"proto": "https", "bindIp": "203.0.113.11", "port": 443, "hostname": "c.example.test"})
+	want(200, c, body, "a second named address")
+	c, body = open(map[string]any{"proto": "https", "bindIp": "203.0.113.10", "port": 443, "hostname": "d.example.test"})
+	want(200, c, body, "another hostname on a named address")
+	// still refused: the same hostname twice on one listener, a raw port on a website's port, and another protocol
+	c, body = open(map[string]any{"proto": "https", "bindIp": "203.0.113.10", "port": 443, "hostname": "b.example.test"})
+	want(400, c, body, "the same hostname twice on one address")
+	c, body = open(map[string]any{"proto": "tcp", "bindIp": "0.0.0.0", "port": 443})
+	want(400, c, body, "a raw port on top of websites")
+	c, body = open(map[string]any{"proto": "http", "bindIp": "203.0.113.10", "port": 443, "hostname": "e.example.test"})
+	want(400, c, body, "http on an https port")
+
+	// the HTTP to HTTPS redirect also uses port 80 at its address
+	c, body = open(map[string]any{"proto": "tcp", "bindIp": "203.0.113.20", "port": 80})
+	want(200, c, body, "a raw port 80 on its own address")
+	c, body = open(map[string]any{"proto": "https", "bindIp": "203.0.113.20", "port": 8443, "hostname": "f.example.test", "redirectHttp": true})
+	want(400, c, body, "a redirect onto a raw port 80")
+	if !strings.Contains(body, "port 80") {
+		t.Errorf("the error should name port 80: %s", body)
+	}
+	c, body = open(map[string]any{"proto": "https", "bindIp": "203.0.113.20", "port": 8443, "hostname": "f.example.test"})
+	want(200, c, body, "the same website without the redirect")
+	c, body = open(map[string]any{"proto": "https", "bindIp": "203.0.113.21", "port": 443, "hostname": "g.example.test", "redirectHttp": true})
+	want(200, c, body, "a redirect where port 80 is free")
+	c, body = open(map[string]any{"proto": "tcp", "bindIp": "203.0.113.21", "port": 80})
+	want(400, c, body, "a raw port 80 where a redirect lives")
+	c, body = open(map[string]any{"proto": "http", "bindIp": "203.0.113.21", "port": 80, "hostname": "h.example.test"})
+	want(200, c, body, "an http website beside a redirect on port 80")
+}