diff --git a/src/vmime/utility/path.cpp b/src/vmime/utility/path.cpp
index aaa3192e..7ce028ff 100644
--- a/src/vmime/utility/path.cpp
+++ b/src/vmime/utility/path.cpp
@@ -292,7 +292,7 @@ path path::fromString(const string& str, const string& sep, const charset& cset)
 }
 
 
-const string path::toString(const string& sep, const charset& cset)
+const string path::toString(const string& sep, const charset& cset) const
 {
 	string str;
 
diff --git a/src/vmime/utility/path.hpp b/src/vmime/utility/path.hpp
index 02fd9ce6..310fa24b 100644
--- a/src/vmime/utility/path.hpp
+++ b/src/vmime/utility/path.hpp
@@ -175,7 +175,7 @@ public:
 	  * vmime::charset::getLocalCharset() to use the default charset of your system)
 	  * @return a string representing this path
 	  */
-	const string toString(const string& sep, const charset& cset);
+	const string toString(const string& sep, const charset& cset) const;
 
 private: