diff --git a/src/libexpr/value-to-xml.cc b/src/libexpr/value-to-xml.cc
index 6f6f4d70e..ace8ed7fe 100644
--- a/src/libexpr/value-to-xml.cc
+++ b/src/libexpr/value-to-xml.cc
@@ -24,8 +24,8 @@ static void printValueAsXML(EvalState & state, bool strict, bool location,
 
 static void posToXML(EvalState & state, XMLAttrs & xmlAttrs, const Pos & pos)
 {
-    // FIXME
-    //xmlAttrs["path"] = pos.file;
+    if (auto path = std::get_if<SourcePath>(&pos.origin))
+        xmlAttrs["path"] = path->path.abs();
     xmlAttrs["line"] = (format("%1%") % pos.line).str();
     xmlAttrs["column"] = (format("%1%") % pos.column).str();
 }