Index: src/OFDeflateStream.m
==================================================================
--- src/OFDeflateStream.m
+++ src/OFDeflateStream.m
@@ -331,11 +331,15 @@
 	_decompression = [self allocMemoryWithSize: sizeof(*_decompression)];
 	memset(_decompression, 0, sizeof(*_decompression));
 
 	/* 0-7 address the bit, 8 means fetch next byte */
 	_decompression->bitIndex = 8;
+#ifdef DEFLATE64
+	_decompression->slidingWindowMask = 0xFFFF;
+#else
 	_decompression->slidingWindowMask = 0x7FFF;
+#endif
 }
 
 - (size_t)lowlevelReadIntoBuffer: (void*)buffer_
 			  length: (size_t)length
 {