diff --git a/amdis/common/Filesystem.hpp b/amdis/common/Filesystem.hpp
index 384aedd031356befc7c37a7c7aa22adabcb2675d..793428bc2017efe96b4b75b6edc4c35f715d1ac8 100644
--- a/amdis/common/Filesystem.hpp
+++ b/amdis/common/Filesystem.hpp
@@ -90,7 +90,7 @@ namespace AMDiS
       bool is_directory() const;
 
       /// Lexicographically compares two paths
-      bool operator==(path const& p)
+      bool operator==(path const& p) const
       {
         return this->string() == p.string();
       }