diff --git a/libs/io/include/psemek/io/memory_stream.hpp b/libs/io/include/psemek/io/memory_stream.hpp
index 5bb98f02..e90102cc 100644
--- a/libs/io/include/psemek/io/memory_stream.hpp
+++ b/libs/io/include/psemek/io/memory_stream.hpp
@@ -55,6 +55,15 @@ namespace psemek::io
 
 		std::size_t read(char * p, std::size_t size) override;
 
+		void advance(std::size_t n)
+		{
+			if (end_ - begin_ < n)
+				throw io::istream_end{};
+			begin_ += n;
+		}
+
+		char const * data() const { return begin_; }
+
 	private:
 		char const * begin_ = nullptr;
 		char const * end_ = nullptr;
@@ -101,6 +110,15 @@ namespace psemek::io
 			std::swap(end_, s.end_);
 		}
 
+		void advance(std::size_t n)
+		{
+			if (end_ - begin_ < n)
+				throw io::istream_end{};
+			begin_ += n;
+		}
+
+		char * data() const { return begin_; }
+
 		std::size_t write(char const * p, std::size_t size) override;
 
 	private: