diff --git a/pkg/proxmox/client.go b/pkg/proxmox/client.go
index 2eec73dae..8b0450425 100644
--- a/pkg/proxmox/client.go
+++ b/pkg/proxmox/client.go
@@ -1460,8 +1460,8 @@ func (fs *VMFileSystem) UnmarshalJSON(data []byte) error {
 	fs.Name = raw.Name
 	fs.Type = raw.Type
 	fs.Mountpoint = raw.Mountpoint
-	if fs.Mountpoint == "" {
-		if normalized, ok := normalizeWindowsDriveMountpoint(raw.Name); ok {
+	if normalized, ok := normalizeWindowsDriveMountpoint(raw.Name); ok {
+		if fs.Mountpoint == "" || isWindowsVolumeGUIDMountpoint(fs.Mountpoint) {
 			fs.Mountpoint = normalized
 		}
 	}
@@ -1490,6 +1490,11 @@ func normalizeWindowsDriveMountpoint(value string) (string, bool) {
 	}
 }
 
+func isWindowsVolumeGUIDMountpoint(value string) bool {
+	value = strings.TrimSpace(strings.ToLower(value))
+	return strings.HasPrefix(value, `\\?\volume{`) && strings.HasSuffix(value, `}\`)
+}
+
 func parseUint64Flexible(value interface{}) (uint64, error) {
 	switch v := value.(type) {
 	case nil:
diff --git a/pkg/proxmox/client_api_more3_test.go b/pkg/proxmox/client_api_more3_test.go
index 5b863f59b..cda726808 100644
--- a/pkg/proxmox/client_api_more3_test.go
+++ b/pkg/proxmox/client_api_more3_test.go
@@ -131,6 +131,44 @@ func TestClientVMFSInfoParsingWindowsNameMountpointFallback(t *testing.T) {
 	}
 }
 
+func TestClientVMFSInfoParsingWindowsVolumeGUIDMountpointFallback(t *testing.T) {
+	client := newTestClient(t, func(w http.ResponseWriter, r *http.Request) {
+		switch r.URL.Path {
+		case "/api2/json/nodes/node1/qemu/100/agent/get-fsinfo":
+			writeJSON(t, w, map[string]interface{}{
+				"data": map[string]interface{}{
+					"result": []map[string]interface{}{
+						{
+							"name":        "C:\\",
+							"type":        "ntfs",
+							"mountpoint":  "\\\\?\\Volume{1234-5678}\\",
+							"total-bytes": 500,
+							"used-bytes":  200,
+						},
+					},
+				},
+			})
+		default:
+			http.NotFound(w, r)
+		}
+	})
+
+	ctx := context.Background()
+	filesystems, err := client.GetVMFSInfo(ctx, "node1", 100)
+	if err != nil {
+		t.Fatalf("GetVMFSInfo error: %v", err)
+	}
+	if len(filesystems) != 1 {
+		t.Fatalf("expected 1 filesystem, got %d", len(filesystems))
+	}
+	if filesystems[0].Mountpoint != "C:\\" {
+		t.Fatalf("expected windows drive-letter mountpoint fallback, got %q", filesystems[0].Mountpoint)
+	}
+	if filesystems[0].Disk != "C:" {
+		t.Fatalf("expected windows drive disk, got %q", filesystems[0].Disk)
+	}
+}
+
 func TestClientVMFSInfoObjectResult(t *testing.T) {
 	client := newTestClient(t, func(w http.ResponseWriter, r *http.Request) {
 		switch r.URL.Path {