diff --git a/internal/api/errors.go b/internal/api/errors.go
index 045feae..6b19c36 100644
--- a/internal/api/errors.go
+++ b/internal/api/errors.go
@@ -1,6 +1,11 @@
 package api
 
-import "net/http"
+import (
+	"errors"
+	"net/http"
+)
+
+var ErrDuplicateAPNSToken = errors.New("duplicate apns token")
 
 func (a *api) errorResponse(w http.ResponseWriter, _ *http.Request, status int, err error) {
 	w.Header().Set("X-Apollo-Error", err.Error())
diff --git a/internal/api/live_activities.go b/internal/api/live_activities.go
index ac509f4..fd8b0d1 100644
--- a/internal/api/live_activities.go
+++ b/internal/api/live_activities.go
@@ -13,7 +13,12 @@ func (a *api) createLiveActivityHandler(w http.ResponseWriter, r *http.Request)
 
 	la := &domain.LiveActivity{}
 	if err := json.NewDecoder(r.Body).Decode(la); err != nil {
-		a.errorResponse(w, r, 500, err)
+		a.errorResponse(w, r, 400, err)
+		return
+	}
+
+	if _, err := a.liveActivityRepo.Get(ctx, la.APNSToken); err == nil {
+		a.errorResponse(w, r, 400, ErrDuplicateAPNSToken)
 		return
 	}