diff --git a/src/nvim/testing.c b/src/nvim/testing.c
index 92747822b4..d9c376dd6a 100644
--- a/src/nvim/testing.c
+++ b/src/nvim/testing.c
@@ -522,14 +522,13 @@ void f_assert_fails(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
     return;
   }
 
-  const char *const cmd = tv_get_string_chk(&argvars[0]);
-
   // trylevel must be zero for a ":throw" command to be considered failed
   trylevel = 0;
   suppress_errthrow = true;
   in_assert_fails = true;
   no_wait_return++;
 
+  const char *const cmd = tv_get_string_chk(&argvars[0]);
   do_cmdline_cmd(cmd);
 
   // reset here for any errors reported below
diff --git a/test/old/testdir/test_assert.vim b/test/old/testdir/test_assert.vim
index 9b65e36e16..e20084515e 100644
--- a/test/old/testdir/test_assert.vim
+++ b/test/old/testdir/test_assert.vim
@@ -327,6 +327,12 @@ func Test_assert_fails_in_try_block()
   endtry
 endfunc
 
+func Test_assert_fails_in_timer()
+  " should not cause a hit-enter prompt, which isn't actually checked here
+  call timer_start(0, {-> assert_fails('call', 'E471:')})
+  sleep 10m
+endfunc
+
 func Test_assert_beeps()
   new
   call assert_equal(0, assert_beeps('normal h'))