diff --git a/fbreader/fbreader/zlibrary/core/src/filesystem/ZLInputStreamDecorator.cpp b/fbreader/fbreader/zlibrary/core/src/filesystem/ZLInputStreamDecorator.cpp
index b44cf9a..719897e 100644
--- a/fbreader/fbreader/zlibrary/core/src/filesystem/ZLInputStreamDecorator.cpp
+++ b/fbreader/fbreader/zlibrary/core/src/filesystem/ZLInputStreamDecorator.cpp
@@ -24,7 +24,7 @@ ZLInputStreamDecorator::ZLInputStreamDecorator(shared_ptr<ZLInputStream> decorat
 
 bool ZLInputStreamDecorator::open() {
 	bool result = myBaseStream->open();
-	myBaseOffset = myBaseStream->offset();
+	if (result) myBaseOffset = myBaseStream->offset();
 	return result;
 }