diff --git a/main.go b/main.go
index f50f9d2..a333add 100644
--- a/main.go
+++ b/main.go
@@ -8,6 +8,8 @@ import (
 	"net/http"
 	"os"
 	"runtime/debug"
+	"strconv"
+	"strings"
 
 	"golang.org/x/crypto/bcrypt"
 
@@ -42,6 +44,11 @@ func main() {
 		baseURL = "http://localhost:8080"
 	}
 
+	allowSignup := false
+	if v := os.Getenv("PODSTALK_ALLOW_SIGNUP"); v != "" {
+		allowSignup = envBool(v)
+	}
+
 	st, err := store.New(dbPath)
 	if err != nil {
 		log.Fatalf("failed to open database: %v", err)
@@ -58,7 +65,7 @@ func main() {
 
 	authMid := &handler.AuthMiddleware{Store: st, Sessions: sessions}
 
-	authH := &handler.AuthHandler{Store: st, Sessions: sessions, Tpl: tpl}
+	authH := &handler.AuthHandler{Store: st, Sessions: sessions, Tpl: tpl, AllowSignup: allowSignup}
 	epH := &handler.EpisodeHandler{
 		Store:     st,
 		Tpl:       tpl,
@@ -157,3 +164,15 @@ func envOrDefault(key, def string) string {
 	}
 	return def
 }
+
+// envBool interprets a string as a truthy boolean.
+func envBool(v string) bool {
+	if b, err := strconv.ParseBool(v); err == nil {
+		return b
+	}
+	switch strings.ToLower(strings.TrimSpace(v)) {
+	case "yes", "on":
+		return true
+	}
+	return false
+}