diff --git a/src/Library/ConfigFilePrivate.cpp b/src/Library/ConfigFilePrivate.cpp
index 8aefa65..40914f7 100644
--- a/src/Library/ConfigFilePrivate.cpp
+++ b/src/Library/ConfigFilePrivate.cpp
@@ -51,7 +51,7 @@ namespace usbguard
 
   void ConfigFilePrivate::open(const std::string& path)
   {
-    _stream.open(path, std::ios::in|std::ios::out);
+    _stream.open(path, std::ios::in);
     if (!_stream.is_open()) {
       throw std::runtime_error("Can't open " + path);
     }