Index: src/GenPoly/Box.cc
===================================================================
--- src/GenPoly/Box.cc	(revision 9a707e4e43b264eeb55851eda9a8efc6c7c78dd1)
+++ src/GenPoly/Box.cc	(revision eada3cfc526a731d1ac85003f73c04f68d7ae037)
@@ -628,6 +628,5 @@
 					} else {
 						// xxx - should this be an assertion?
-						std::string x = env ? toString( *env ) : "missing env";
-						throw SemanticError( x + "\n" + "unbound type variable: " + tyParm->first + " in application ", appExpr );
+						throw SemanticError( toString( *env, "\nunbound type variable: ", tyParm->first, " in application " ), appExpr );
 					} // if
 				} // if
@@ -706,7 +705,4 @@
 				if ( concrete == 0 ) {
 					return typeInst;
-					// xxx - should this be an assertion?
-//					std::string x = env ? toString( *env ) : "missing env";
-//					throw SemanticError( x + "\n" + "Unbound type variable " + typeInst->get_name() + " in ", appExpr );
 				} // if
 				return concrete;