Index: src/OFMutableZooArchiveEntry.m
==================================================================
--- src/OFMutableZooArchiveEntry.m
+++ src/OFMutableZooArchiveEntry.m
@@ -24,10 +24,16 @@
 @implementation OFMutableZooArchiveEntry
 @dynamic headerType, compressionMethod, modificationDate, CRC16;
 @dynamic uncompressedSize, compressedSize, minVersionNeeded, deleted;
 @dynamic fileComment, fileName, operatingSystemIdentifier, POSIXPermissions;
 @dynamic timeZone;
+/*
+ * The following properties are not implemented, but old Apple GCC requries
+ * @dynamic for @optional properties.
+ */
+@dynamic ownerAccountID, groupOwnerAccountID, ownerAccountName;
+@dynamic groupOwnerAccountName;
 
 + (instancetype)entryWithFileName: (OFString *)fileName
 {
 	return [[[self alloc] initWithFileName: fileName] autorelease];
 }

Index: src/OFZooArchiveEntry.m
==================================================================
--- src/OFZooArchiveEntry.m
+++ src/OFZooArchiveEntry.m
@@ -26,10 +26,17 @@
 #import "OFInvalidFormatException.h"
 #import "OFOutOfRangeException.h"
 #import "OFUnsupportedVersionException.h"
 
 @implementation OFZooArchiveEntry
+/*
+ * The following properties are not implemented, but old Apple GCC requries
+ * @dynamic for @optional properties.
+ */
+@dynamic ownerAccountID, groupOwnerAccountID, ownerAccountName;
+@dynamic groupOwnerAccountName;
+
 - (instancetype)init
 {
 	OF_INVALID_INIT_METHOD
 }