@@ -18,10 +18,31 @@
 
 @class OFInflateStream;
 
 OF_ASSUME_NONNULL_BEGIN
 
+/**
+ * @brief The operating system on which compressed the data.
+ */
+typedef enum OFGZIPStreamOperatingSystem {
+	OFGZIPStreamOperatingSystemFAT	       =   0,
+	OFGZIPStreamOperatingSystemAmiga       =   1,
+	OFGZIPStreamOperatingSystemVMS	       =   2,
+	OFGZIPStreamOperatingSystemUNIX	       =   3,
+	OFGZIPStreamOperatingSystemVM_CMS      =   4,
+	OFGZIPStreamOperatingSystemAtariTOS    =   5,
+	OFGZIPStreamOperatingSystemHPFS	       =   6,
+	OFGZIPStreamOperatingSystemMacintosh   =   7,
+	OFGZIPStreamOperatingSystemZSystem     =   8,
+	OFGZIPStreamOperatingSystemCP_M	       =   9,
+	OFGZIPStreamOperatingSystemTOPS20      =  10,
+	OFGZIPStreamOperatingSystemNTFS	       =  11,
+	OFGZIPStreamOperatingSystemQDO	       =  12,
+	OFGZIPStreamOperatingSystemAcornRISCOS =  13,
+	OFGZIPStreamOperatingSystemUnknown     = 255
+} OFGZIPStreamOperatingSystem;
+
 /**
  * @class OFGZIPStream OFGZIPStream.h ObjFW/OFGZIPStream.h
  *
  * @brief A class that handles GZIP compression and decompression transparently
  *	  for an underlying stream.
@@ -29,52 +50,36 @@
 OF_SUBCLASSING_RESTRICTED
 @interface OFGZIPStream: OFStream
 {
 	OFStream *_stream;
 	OFInflateStream *_Nullable _inflateStream;
-	enum of_gzip_stream_state {
-		OF_GZIP_STREAM_ID1,
-		OF_GZIP_STREAM_ID2,
-		OF_GZIP_STREAM_COMPRESSION_METHOD,
-		OF_GZIP_STREAM_FLAGS,
-		OF_GZIP_STREAM_MODIFICATION_TIME,
-		OF_GZIP_STREAM_EXTRA_FLAGS,
-		OF_GZIP_STREAM_OPERATING_SYSTEM,
-		OF_GZIP_STREAM_EXTRA_LENGTH,
-		OF_GZIP_STREAM_EXTRA,
-		OF_GZIP_STREAM_NAME,
-		OF_GZIP_STREAM_COMMENT,
-		OF_GZIP_STREAM_HEADER_CRC16,
-		OF_GZIP_STREAM_DATA,
-		OF_GZIP_STREAM_CRC32,
-		OF_GZIP_STREAM_UNCOMPRESSED_SIZE
+	enum {
+		OFGZIPStreamStateID1,
+		OFGZIPStreamStateID2,
+		OFGZIPStreamStateCompressionMethod,
+		OFGZIPStreamStateFlags,
+		OFGZIPStreamStateModificationDate,
+		OFGZIPStreamStateExtraFlags,
+		OFGZIPStreamStateOperatingSystem,
+		OFGZIPStreamStateExtraLength,
+		OFGZIPStreamStateExtra,
+		OFGZIPStreamStateName,
+		OFGZIPStreamStateComment,
+		OFGZIPStreamStateHeaderCRC16,
+		OFGZIPStreamStateData,
+		OFGZIPStreamStateCRC32,
+		OFGZIPStreamStateUncompressedSize
 	} _state;
-	enum of_gzip_stream_flags {
-		OF_GZIP_STREAM_FLAG_TEXT	 = 0x01,
-		OF_GZIP_STREAM_FLAG_HEADER_CRC16 = 0x02,
-		OF_GZIP_STREAM_FLAG_EXTRA	 = 0x04,
-		OF_GZIP_STREAM_FLAG_NAME	 = 0x08,
-		OF_GZIP_STREAM_FLAG_COMMENT	 = 0x10
+	enum {
+		OFGZIPStreamFlagText	    = 0x01,
+		OFGZIPStreamFlagHeaderCRC16 = 0x02,
+		OFGZIPStreamFlagExtra	    = 0x04,
+		OFGZIPStreamFlagName	    = 0x08,
+		OFGZIPStreamFlagComment	    = 0x10
 	} _flags;
 	uint8_t _extraFlags;
-	enum of_gzip_stream_operating_system {
-		OF_GZIP_STREAM_OPERATING_SYSTEM_FAT		=   0,
-		OF_GZIP_STREAM_OPERATING_SYSTEM_AMIGA		=   1,
-		OF_GZIP_STREAM_OPERATING_SYSTEM_VMS		=   2,
-		OF_GZIP_STREAM_OPERATING_SYSTEM_UNIX		=   3,
-		OF_GZIP_STREAM_OPERATING_SYSTEM_VM_CMS		=   4,
-		OF_GZIP_STREAM_OPERATING_SYSTEM_ATARI_TOS	=   5,
-		OF_GZIP_STREAM_OPERATING_SYSTEM_HPFS		=   6,
-		OF_GZIP_STREAM_OPERATING_SYSTEM_MACINTOSH	=   7,
-		OF_GZIP_STREAM_OPERATING_SYSTEM_Z_SYSTEM	=   8,
-		OF_GZIP_STREAM_OPERATING_SYSTEM_CP_M		=   9,
-		OF_GZIP_STREAM_OPERATING_SYSTEM_TOPS_20		=  10,
-		OF_GZIP_STREAM_OPERATING_SYSTEM_NTFS		=  11,
-		OF_GZIP_STREAM_OPERATING_SYSTEM_QDO		=  12,
-		OF_GZIP_STREAM_OPERATING_SYSTEM_ACORN_RISC_OS	=  13,
-		OF_GZIP_STREAM_OPERATING_SYSTEM_UNKNOWN		= 255
-	} _operatingSystemMadeOn;
+	OFGZIPStreamOperatingSystem _operatingSystemMadeOn;
 	size_t _bytesRead;
 	uint8_t _buffer[4];
 	OFDate *_Nullable _modificationDate;
 	uint16_t _extraLength;
 	uint32_t _CRC32, _uncompressedSize;
@@ -85,11 +90,11 @@
  *
  * This property is only guaranteed to be available once @ref atEndOfStream is
  * true.
  */
 @property (readonly, nonatomic)
-    enum of_gzip_stream_operating_system operatingSystemMadeOn;
+    OFGZIPStreamOperatingSystem operatingSystemMadeOn;
 
 /**
  * @brief The modification date of the original file.
  *
  * This property is only guaranteed to be available once @ref atEndOfStream is