diff --git a/R/ParamSet.R b/R/ParamSet.R
index 4dcec206..1ea05ae6 100644
--- a/R/ParamSet.R
+++ b/R/ParamSet.R
@@ -432,7 +432,7 @@ ParamSet = R6Class("ParamSet",
         xs_nontune = discard(xs, inherits, "TuneToken")
 
         # only had TuneTokens, nothing else to check here.
-        if (!length(xs_nontune)) {
+        if (!length(xs_nontune) && !some(xs, is, "InternalTuneToken")) {
           return(trueret)
         }
       } else {
diff --git a/tests/testthat/test_to_tune.R b/tests/testthat/test_to_tune.R
index 1dca0c35..97caf872 100644
--- a/tests/testthat/test_to_tune.R
+++ b/tests/testthat/test_to_tune.R
@@ -456,3 +456,11 @@ test_that("internal and aggr", {
   )
   expect_equal(param_set$search_space()$aggr_internal_tuned_values(list(a = list(1, 2, 3))), list(a = -60))
 })
+
+test_that("cannot mark non-int-tuneable parameters for int tuning", {
+  p = ps(x = p_int(lower = 0L))
+  expect_error(
+    p$set_values(x = to_tune(upper = 1000, internal = TRUE, aggr = function(x) round(mean(unlist(x))))),
+    "Trying to assign"
+  )
+})