diff --git a/R/OptimInstance.R b/R/OptimInstance.R
index 0ff08c8d..1ce8e468 100644
--- a/R/OptimInstance.R
+++ b/R/OptimInstance.R
@@ -107,7 +107,9 @@ OptimInstance = R6Class("OptimInstance",
     #'   columns for extra information.
     #' @param y (`numeric(1)`)\cr
     #'   Optimal outcome.
-    assign_result = function(xdt, y) {
+    #' @param ... (`any`)\cr
+    #' ignored.
+    assign_result = function(xdt, y, ...) {
       stop("Abstract class")
     },
 
diff --git a/R/Optimizer.R b/R/Optimizer.R
index b81db536..5102b6b6 100644
--- a/R/Optimizer.R
+++ b/R/Optimizer.R
@@ -166,19 +166,18 @@ Optimizer = R6Class("Optimizer",
 assign_result_default = function(inst) {
   assert_r6(inst, "OptimInstance")
 
-  res = inst$archive$best()
+  xydt = inst$archive$best()
   ids = inst$search_space$ids()
-  # workaround until ... works
-  if ("internal_tuned_values" %in% names(res)) ids = c(ids, "internal_tuned_values")
-  xdt = res[, ids, with = FALSE]
+  xdt = xydt[, ids, with = FALSE]
 
   if (inherits(inst, "OptimInstanceBatchMultiCrit") || inherits(inst, "OptimInstanceAsyncMultiCrit")) {
-    ydt = res[, inst$archive$cols_y, with = FALSE]
-    inst$assign_result(xdt, ydt)
+    ydt = xydt[, inst$archive$cols_y, with = FALSE]
+    # upstream packages might extract extra columns from xydt
+    inst$assign_result(xdt, ydt, xydt = xydt)
   } else {
     # unlist keeps name!
-    y = unlist(res[, inst$archive$cols_y, with = FALSE])
-    inst$assign_result(xdt, y)
+    y = unlist(xydt[, inst$archive$cols_y, with = FALSE])
+    inst$assign_result(xdt, y, xydt = xydt)
   }
 
   invisible(NULL)
diff --git a/man/OptimInstance.Rd b/man/OptimInstance.Rd
index e1b5381b..90bb285b 100644
--- a/man/OptimInstance.Rd
+++ b/man/OptimInstance.Rd
@@ -158,7 +158,7 @@ Printer.
 The \link{Optimizer} object writes the best found point and estimated performance value here.
 For internal use.
 \subsection{Usage}{
-\if{html}{\out{<div class="r">}}\preformatted{OptimInstance$assign_result(xdt, y)}\if{html}{\out{</div>}}
+\if{html}{\out{<div class="r">}}\preformatted{OptimInstance$assign_result(xdt, y, ...)}\if{html}{\out{</div>}}
 }
 
 \subsection{Arguments}{
@@ -171,6 +171,9 @@ columns for extra information.}
 
 \item{\code{y}}{(\code{numeric(1)})\cr
 Optimal outcome.}
+
+\item{\code{...}}{(\code{any})\cr
+ignored.}
 }
 \if{html}{\out{</div>}}
 }
diff --git a/tests/testthat/test_TerminatorStagnationHypervolume.R b/tests/testthat/test_TerminatorStagnationHypervolume.R
index cb1fdc75..38a654ac 100644
--- a/tests/testthat/test_TerminatorStagnationHypervolume.R
+++ b/tests/testthat/test_TerminatorStagnationHypervolume.R
@@ -1,4 +1,6 @@
 test_that("TerminatorStagnationHypervolume works", {
+  skip_if_not_installed("emoa")
+
   terminator = trm("stagnation_hypervolume")
   terminator$param_set$values$iters = 5
   terminator$param_set$values$threshold = 0