diff --git a/tests/testthat/test-memoise.R b/tests/testthat/test-memoise.R
index 4ff7dda..b36032b 100644
--- a/tests/testthat/test-memoise.R
+++ b/tests/testthat/test-memoise.R
@@ -327,19 +327,28 @@ test_that("omit_args respected", {
 
   expect_true(identical(res1, res2))
 
-  # Also works for default args
-  f <- function(n, x = rnorm(1)) {
-    rnorm(n)
+  # Also works for default arguments
+  a <- 0
+  f <- function(x = a) {
+    a <<- a + 1
+    a
   }
-  mem_f <- memoise(f)
-  expect_false(identical(res1, res2))
-  res1 <- mem_f(1)
-  res2 <- mem_f(1)
 
+  # everytime `f()` is called its value increases by 1
+  expect_equal(f(), 1)
+  expect_equal(f(), 2)
+
+  # it still increases by one when memoised as the argument `x` changes
+  a <- 0
+  mem_f <- memoise::memoise(f)
+  expect_equal(mem_f(), 1)
+  expect_equal(mem_f(), 2)
+
+  # but `x` can be ignored via `omit_args`
+  a <- 0
   mem_f2 <- memoise(f, omit_args = "x")
-  res1 <- mem_f2(1)
-  res2 <- mem_f2(1)
-  expect_true(identical(res1, res2))
+  expect_equal(mem_f2(), 1)
+  expect_equal(mem_f2(), 1)
 })
 
 context("has_cache")