diff --git a/src/vmime/parameter.hpp b/src/vmime/parameter.hpp
index a97408b9..d1e6ea72 100644
--- a/src/vmime/parameter.hpp
+++ b/src/vmime/parameter.hpp
@@ -44,8 +44,26 @@ private:
 
 public:
 
-	explicit parameter(const string& name);
+	/** Construct a parameter with no value.
+	  * Charset is set to the current locale charset.
+	  *
+	  * @param name parameter name
+	  */
+	parameter(const string& name);
+
+	/** Construct a parameter given a name and a value.
+	  *
+	  * @param name parameter name
+	  * @param value parameter value
+	  */
 	parameter(const string& name, const word& value);
+
+	/** Construct a parameter given a name and a string value
+	  * expressed in the current locale charset.
+	  *
+	  * @param name parameter name
+	  * @param value parameter value
+	  */
 	parameter(const string& name, const string& value);
 
 
diff --git a/tests/parser/parameterTest.cpp b/tests/parser/parameterTest.cpp
index cf8f8477..41af3fdd 100644
--- a/tests/parser/parameterTest.cpp
+++ b/tests/parser/parameterTest.cpp
@@ -467,7 +467,9 @@ VMIME_TEST_SUITE_BEGIN(parameterTest)
 	void testEncodeTSpecialsInRFC2231()
 	{
 		VASSERT_EQ("1", "filename*=UTF-8''my_file_name_%C3%B6%C3%A4%C3%BC_%281%29.txt",
-			vmime::make_shared <vmime::parameter>("filename", "my_file_name_\xc3\xb6\xc3\xa4\xc3\xbc_(1).txt")->generate());
+			vmime::make_shared <vmime::parameter>
+				("filename",
+				 vmime::word("my_file_name_\xc3\xb6\xc3\xa4\xc3\xbc_(1).txt", "UTF-8"))->generate());
 	}
 
 	void testWhitespaceBreaksTheValue()