@@ -20,10 +20,11 @@
 OF_ASSUME_NONNULL_BEGIN
 
 @class OFArray OF_GENERIC(ObjectType);
 @class OFData;
 @class OFDate;
+@class OFMutableArray OF_GENERIC(ObjectType);
 @class OFNumber;
 @class OFString;
 
 /*!
  * @class OFLHAArchiveEntry OFLHAArchiveEntry.h ObjFW/OFLHAArchiveEntry.h
@@ -44,11 +45,11 @@
 	uint8_t _operatingSystemIdentifier;
 	OFString *_Nullable _fileComment;
 	OFNumber *_Nullable _mode, *_Nullable _UID, *_Nullable _GID;
 	OFString *_Nullable _owner, *_Nullable _group;
 	OFDate *_Nullable _modificationDate;
-	OFArray OF_GENERIC(OFData *) *_extensions;
+	OFMutableArray OF_GENERIC(OFData *) *_extensions;
 }
 
 /*!
  * @brief The file name of the entry.
  */