Index: src/OFZIPArchive.m
==================================================================
--- src/OFZIPArchive.m
+++ src/OFZIPArchive.m
@@ -659,16 +659,18 @@
 						 encoding: encoding] copy];
 		if (extraFieldLength > 0)
 			extraField = [[[stream readDataWithCount:
 			    extraFieldLength] mutableCopy] autorelease];
 
-		of_zip_archive_entry_extra_field_find(_extraField,
+		of_zip_archive_entry_extra_field_find(extraField,
 		    OF_ZIP_ARCHIVE_ENTRY_EXTRA_FIELD_ZIP64, &ZIP64Size);
 
 		if (ZIP64Index != OF_NOT_FOUND) {
 			const uint8_t *ZIP64 =
 			    [extraField itemAtIndex: ZIP64Index];
+			of_range_t range =
+			    of_range(ZIP64Index - 4, ZIP64Size + 4);
 
 			if (_uncompressedSize == 0xFFFFFFFF)
 				_uncompressedSize = of_zip_archive_read_field64(
 				    &ZIP64, &ZIP64Size);
 			if (_compressedSize == 0xFFFFFFFF)
@@ -676,16 +678,17 @@
 				    &ZIP64, &ZIP64Size);
 
 			if (ZIP64Size > 0)
 				@throw [OFInvalidFormatException exception];
 
-			[extraField removeItemsInRange:
-			    of_range(ZIP64Index - 4, ZIP64Size + 4)];
+			[extraField removeItemsInRange: range];
 		}
 
-		[extraField makeImmutable];
-		_extraField = [extraField copy];
+		if ([extraField count] > 0) {
+			[extraField makeImmutable];
+			_extraField = [extraField copy];
+		}
 
 		objc_autoreleasePoolPop(pool);
 	} @catch (id e) {
 		[self release];
 		@throw e;

Index: src/OFZIPArchiveEntry.m
==================================================================
--- src/OFZIPArchiveEntry.m
+++ src/OFZIPArchiveEntry.m
@@ -217,16 +217,18 @@
 		if (fileCommentLength > 0)
 			_fileComment = [[stream
 			    readStringWithLength: fileCommentLength
 					encoding: encoding] copy];
 
-		ZIP64Index = of_zip_archive_entry_extra_field_find(_extraField,
+		ZIP64Index = of_zip_archive_entry_extra_field_find(extraField,
 		    OF_ZIP_ARCHIVE_ENTRY_EXTRA_FIELD_ZIP64, &ZIP64Size);
 
 		if (ZIP64Index != OF_NOT_FOUND) {
 			const uint8_t *ZIP64 =
-			    [_extraField itemAtIndex: ZIP64Index];
+			    [extraField itemAtIndex: ZIP64Index];
+			of_range_t range =
+			    of_range(ZIP64Index - 4, ZIP64Size + 4);
 
 			if (_uncompressedSize == 0xFFFFFFFF)
 				_uncompressedSize = of_zip_archive_read_field64(
 				    &ZIP64, &ZIP64Size);
 			if (_compressedSize == 0xFFFFFFFF)
@@ -241,16 +243,17 @@
 				    &ZIP64, &ZIP64Size);
 
 			if (ZIP64Size > 0 || _localFileHeaderOffset < 0)
 				@throw [OFInvalidFormatException exception];
 
-			[extraField removeItemsInRange:
-			    of_range(ZIP64Index - 4, ZIP64Size + 4)];
+			[extraField removeItemsInRange: range];
 		}
 
-		[extraField makeImmutable];
-		_extraField = [extraField copy];
+		if ([extraField count] > 0) {
+			[extraField makeImmutable];
+			_extraField = [extraField copy];
+		}
 
 		objc_autoreleasePoolPop(pool);
 	} @catch (id e) {
 		[self release];
 		@throw e;