Index: src/OFZIPArchive.m
==================================================================
--- src/OFZIPArchive.m
+++ src/OFZIPArchive.m
@@ -433,10 +433,13 @@
 	void *pool = objc_autoreleasePoolPush();
 	OFZIPArchiveEntry *entry;
 	OFZIPArchiveLocalFileHeader *localFileHeader;
 	int64_t offset64;
 
+	if (_stream == nil)
+		@throw [OFNotOpenException exceptionWithObject: self];
+
 	if (_mode != modeRead)
 		@throw [OFInvalidArgumentException exception];
 
 	if ((entry = [_pathToEntryMap objectForKey: path]) == nil)
 		@throw [OFOpenItemFailedException exceptionWithPath: path
@@ -483,10 +486,13 @@
 	OFMutableZIPArchiveEntry *entry;
 	OFString *fileName;
 	OFData *extraField;
 	uint16_t fileNameLength, extraFieldLength;
 
+	if (_stream == nil)
+		@throw [OFNotOpenException exceptionWithObject: self];
+
 	if (_mode != modeWrite && _mode != modeAppend)
 		@throw [OFInvalidArgumentException exception];
 
 	pool = objc_autoreleasePoolPush();
 	entry = [[entry_ mutableCopy] autorelease];