diff --git a/src/Buffer.cpp b/src/Buffer.cpp
index 5138c4227c..dec742f334 100644
--- a/src/Buffer.cpp
+++ b/src/Buffer.cpp
@@ -685,6 +685,8 @@ bool Buffer::readFile(FileName const & filename)
 {
 	FileName fname(filename);
 
+	params().compressed = fname.isZippedFile();
+
 	// remove dummy empty par
 	paragraphs().clear();
 	Lexer lex;