diff --git a/agent-linux/main.go b/agent-linux/main.go
index c46e0e5..a970b01 100644
--- a/agent-linux/main.go
+++ b/agent-linux/main.go
@@ -184,6 +184,7 @@ func sendHeartbeat(c *client.Client, agentID string) error {
 	req := map[string]interface{}{
 		"agent_id":      agentID,
 		"agent_version": Version,
+		"platform":      "linux",
 		"system_data":   systemData,
 	}
 
diff --git a/backend/api/handlers.go b/backend/api/handlers.go
index 8792e59..feb1545 100644
--- a/backend/api/handlers.go
+++ b/backend/api/handlers.go
@@ -263,9 +263,13 @@ func (h *Handler) heartbeat(w http.ResponseWriter, r *http.Request) {
 
 	resp := models.HeartbeatResponse{Message: "OK"}
 
-	// Pruefen ob Update ansteht (default freebsd fuer OPNsense)
+	// Pruefen ob Update ansteht — Plattform aus Heartbeat-Request verwenden
 	if h.db.IsUpdateRequested(req.AgentID) {
-		version, hash, _, err := h.db.GetFirmwareInfo("freebsd")
+		platform := req.Platform
+		if platform == "" {
+			platform = "freebsd" // Default fuer OPNsense Agents ohne Platform-Feld
+		}
+		version, hash, _, err := h.db.GetFirmwareInfo(platform)
 		if err != nil {
 			// Keine Firmware vorhanden — Flag sinnlos, loeschen
 			h.db.ClearUpdateRequest(req.AgentID)
diff --git a/backend/models/system.go b/backend/models/system.go
index bc8412a..d04dd2d 100644
--- a/backend/models/system.go
+++ b/backend/models/system.go
@@ -282,6 +282,7 @@ type CaddyData struct {
 type HeartbeatRequest struct {
 	AgentID      string     `json:"agent_id"`
 	AgentVersion string     `json:"agent_version,omitempty"`
+	Platform     string     `json:"platform,omitempty"`
 	SystemData   SystemData `json:"system_data"`
 }