1 files changed, 5 insertions, 2 deletions
diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh
index 25798cac6..ec6fd3190 100644
--- a/src/libexpr/nixexpr.hh
+++ b/src/libexpr/nixexpr.hh
@@ -2,6 +2,7 @@
 
 #include "value.hh"
 #include "symbol-table.hh"
+#include "error.hh"
 
 #include <map>
 
@@ -235,8 +236,10 @@ struct ExprLambda : Expr
         : pos(pos), arg(arg), matchAttrs(matchAttrs), formals(formals), body(body)
     {
         if (!arg.empty() && formals && formals->argNames.find(arg) != formals->argNames.end())
-            throw ParseError(format("duplicate formal function argument '%1%' at %2%")
-                % arg % pos);
+            throw ParseError({
+                .hint = hintfmt("duplicate formal function argument '%1%'", arg),
+                .nixCode = NixCode { .errPos = pos }
+            });
     };
     void setName(Symbol & name);
     string showNamePos() const;