         
         public var pcs: ColorSpaceSignature {
             get {
-                return ColorSpaceSignature(rawValue: UInt32(bigEndian: _pcs))!
+                return ColorSpaceSignature(rawValue: UInt32(bigEndian: _pcs)) ?? .unknown
             }
             set {
                 _pcs = newValue.rawValue.bigEndian

extension iccProfile.Header {
    
    public enum ClassSignature: UInt32 {
        
        case input                     = 0x73636E72  /* 'scnr' */
        case display                   = 0x6D6E7472  /* 'mntr' */

        
        public var deviceClass: ClassSignature {
            get {
                return ClassSignature(rawValue: UInt32(bigEndian: _deviceClass)) ?? .unknown
            }
            set {
                _deviceClass = newValue.rawValue.bigEndian
