diff --git a/src/VCBackend.cpp b/src/VCBackend.cpp
index b395a0d2b2..3eeb3d6a3e 100644
--- a/src/VCBackend.cpp
+++ b/src/VCBackend.cpp
@@ -170,6 +170,8 @@ void RCS::scanMaster()
 	LYXERR(Debug::LYXVC, "LyXVC::RCS: scanMaster: " << master_);
 
 	ifstream ifs(master_.toFilesystemEncoding().c_str());
+	// limit the size of strings we read to avoid memory problems
+	ifs >> setw(65636);
 
 	string token;
 	bool read_enough = false;