Index: src/OFMutableTarArchiveEntry.m
==================================================================
--- src/OFMutableTarArchiveEntry.m
+++ src/OFMutableTarArchiveEntry.m
@@ -15,10 +15,12 @@
  */
 
 #include "config.h"
 
 #import "OFMutableTarArchiveEntry.h"
+#import "OFString.h"
+#import "OFDate.h"
 
 @implementation OFMutableTarArchiveEntry
 @dynamic fileName, mode, UID, GID, size, modificationDate, type, targetFileName;
 @dynamic owner, group, deviceMajor, deviceMinor;
 

Index: src/OFTarArchiveEntry.h
==================================================================
--- src/OFTarArchiveEntry.h
+++ src/OFTarArchiveEntry.h
@@ -61,11 +61,11 @@
 }
 
 /*!
  * The file name of the entry.
  */
-@property (readonly, nonatomic) OFString *fileName;
+@property (readonly, nonatomic, copy) OFString *fileName;
 
 /*!
  * The mode of the entry.
  */
 @property (readonly, nonatomic) uint16_t mode;
@@ -86,11 +86,11 @@
 @property (readonly, nonatomic) uint64_t size;
 
 /*!
  * The date of the last modification of the file.
  */
-@property (readonly, nonatomic) OFDate *modificationDate;
+@property (readonly, nonatomic, retain) OFDate *modificationDate;
 
 /*!
  * The type of the archive entry.
  *
  * See @ref of_tar_archive_entry_type_t.
@@ -98,21 +98,22 @@
 @property (readonly, nonatomic) of_tar_archive_entry_type_t type;
 
 /*!
  * The file name of the target (for a hard link or symbolic link).
  */
-@property OF_NULLABLE_PROPERTY (readonly, nonatomic) OFString *targetFileName;
+@property OF_NULLABLE_PROPERTY (readonly, nonatomic, copy)
+    OFString *targetFileName;
 
 /*!
  * The owner of the file.
  */
-@property OF_NULLABLE_PROPERTY (readonly, nonatomic) OFString *owner;
+@property OF_NULLABLE_PROPERTY (readonly, nonatomic, copy) OFString *owner;
 
 /*!
  * The group of the file.
  */
-@property OF_NULLABLE_PROPERTY (readonly, nonatomic) OFString *group;
+@property OF_NULLABLE_PROPERTY (readonly, nonatomic, copy) OFString *group;
 
 /*!
  * The device major (if the file is a device).
  */
 @property (readonly, nonatomic) uint32_t deviceMajor;

Index: src/OFZIPArchiveEntry.h
==================================================================
--- src/OFZIPArchiveEntry.h
+++ src/OFZIPArchiveEntry.h
@@ -104,23 +104,24 @@
 }
 
 /*!
  * The file name of the entry.
  */
-@property (readonly, nonatomic) OFString *fileName;
+@property (readonly, nonatomic, copy) OFString *fileName;
 
 /*!
  * The comment of the entry's file.
  */
-@property OF_NULLABLE_PROPERTY (readonly, nonatomic) OFString *fileComment;
+@property OF_NULLABLE_PROPERTY (readonly, nonatomic, copy)
+    OFString *fileComment;
 
 /*!
  * The extra field of the entry.
  *
  * The item size *must* be 1!
  */
-@property OF_NULLABLE_PROPERTY (readonly, nonatomic) OFData *extraField;
+@property OF_NULLABLE_PROPERTY (readonly, nonatomic, copy) OFData *extraField;
 
 /*!
  * The version which made the entry.
  *
  * The lower 8 bits are the ZIP specification version.@n
@@ -141,11 +142,11 @@
 /*!
  * The last modification date of the entry's file.
  *
  * @note Due to limitations of the ZIP format, this has only 2 second precision.
  */
-@property (readonly, nonatomic) OFDate *modificationDate;
+@property (readonly, nonatomic, retain) OFDate *modificationDate;
 
 /*!
  * The compression method of the entry.
  *
  * Supported values are: