diff --git a/libs/pbd/enumwriter.cc b/libs/pbd/enumwriter.cc
index 3ce296c664..6d911b2dea 100644
--- a/libs/pbd/enumwriter.cc
+++ b/libs/pbd/enumwriter.cc
@@ -127,7 +127,7 @@ EnumWriter::write (string type, int value)
 
 	if (x == registry.end()) {
 		error << string_compose (_("EnumWriter: unknown enumeration type \"%1\""), type) << endmsg;
-		throw unknown_enumeration();
+		throw unknown_enumeration (type);
 	}
 
 	if (x->second.bitwise) {
@@ -144,7 +144,7 @@ EnumWriter::read (string type, string value)
 
 	if (x == registry.end()) {
 		error << string_compose (_("EnumWriter: unknown enumeration type \"%1\""), type) << endmsg;
-		throw unknown_enumeration();
+		throw unknown_enumeration (type);
 	}
 
 	if (x->second.bitwise) {
@@ -267,7 +267,7 @@ EnumWriter::read_bits (EnumRegistration& er, string str)
 	} while (true);
 
 	if (!found) {
-		throw unknown_enumeration();
+		throw unknown_enumeration (str);
 	}
 
 	return result;
@@ -316,7 +316,7 @@ EnumWriter::read_distinct (EnumRegistration& er, string str)
 		}
 	}
 
-	throw unknown_enumeration();
+	throw unknown_enumeration(str);
 }
 
 void
diff --git a/libs/pbd/pbd/enumwriter.h b/libs/pbd/pbd/enumwriter.h
index 600f59bf29..95f1ea9e9f 100644
--- a/libs/pbd/pbd/enumwriter.h
+++ b/libs/pbd/pbd/enumwriter.h
@@ -25,13 +25,26 @@
 #include <string>
 #include <vector>
 #include <exception>
-
+#include <sstream>
 
 namespace PBD {
 
 class unknown_enumeration : public std::exception {
   public:
-	virtual const char *what() const throw() { return "unknown enumerator in PBD::EnumWriter"; }
+	unknown_enumeration (std::string const & e) throw() {
+		std::stringstream s;
+		s << "unknown enumerator " << e << " in PBD::EnumWriter";
+		_message = s.str ();
+	}
+
+	~unknown_enumeration () throw() {}
+	
+	virtual const char *what() const throw() {
+		return _message.c_str();
+	}
+
+private:
+	std::string _message;
 };
 
 class EnumWriter {