diff --git a/testcases/t/553-popup_during_fullscreen.t b/testcases/t/553-popup_during_fullscreen.t
new file mode 100644
index 00000000..79861d22
--- /dev/null
+++ b/testcases/t/553-popup_during_fullscreen.t
@@ -0,0 +1,127 @@
+#!perl
+# vim:ts=4:sw=4:expandtab
+#
+# Please read the following documents before working on tests:
+# • https://build.i3wm.org/docs/testsuite.html
+#   (or docs/testsuite)
+#
+# • https://build.i3wm.org/docs/lib-i3test.html
+#   (alternatively: perldoc ./testcases/lib/i3test.pm)
+#
+# • https://build.i3wm.org/docs/ipc.html
+#   (or docs/ipc)
+#
+# • https://i3wm.org/downloads/modern_perl_a4.pdf
+#   (unless you are already familiar with Perl)
+#
+# Test popup_during_fullscreen option
+use i3test i3_autostart => 0;
+use i3test::XTEST;
+
+sub setup {
+    kill_all_windows;
+
+    my $ws = fresh_workspace;
+    my $w1 = open_window;
+    cmd 'fullscreen';
+    is_num_fullscreen($ws, 1, 'sanity check: one fullscreen window');
+    return ($ws, $w1);
+}
+
+sub open_transient_for {
+    my $for = shift;
+    my $w = open_window({ dont_map => 1, rect => [ 30, 30, 50, 50 ] });
+    $w->transient_for($for);
+    $w->map;
+    sync_with_i3;
+    return $w;
+}
+
+sub open_without_map_wait {
+    my $w = open_window({ dont_map => 1 });
+    $w->map;
+    sync_with_i3;
+    return $w;
+}
+
+################################################################################
+# Test popup_during_fullscreen ignore
+################################################################################
+
+my $config = <<EOT;
+# i3 config file (v4)
+font -misc-fixed-medium-r-normal--13-120-75-75-C-70-iso10646-1
+
+popup_during_fullscreen ignore
+EOT
+my $pid = launch_with_config($config);
+
+my ($ws, $w1) = setup;
+
+my $w2 = open_transient_for($w1);
+is_num_fullscreen($ws, 1, 'still one fullscren window');
+is($x->input_focus, $w1->id, 'fullscreen window still focused');
+
+open_without_map_wait;
+is_num_fullscreen($ws, 1, 'still one fullscren window');
+is($x->input_focus, $w1->id, 'fullscreen window focused');
+
+exit_gracefully($pid);
+
+################################################################################
+# Test popup_during_fullscreen leave_fullscreen
+################################################################################
+
+$config = <<EOT;
+# i3 config file (v4)
+font -misc-fixed-medium-r-normal--13-120-75-75-C-70-iso10646-1
+
+popup_during_fullscreen leave_fullscreen
+EOT
+$pid = launch_with_config($config);
+
+($ws, $w1) = setup;
+
+# Fullscreen disabled when transient windows open
+$w2 = open_transient_for($w1);
+is_num_fullscreen($ws, 0, 'no fullscren window');
+# XXX: Arguably a bug but leave_fullscreen does not change focus
+is($x->input_focus, $w1->id, 'fullscreen window focused');
+
+# Fullscreen stays when regular windows open
+$w1->fullscreen(1);
+open_without_map_wait;
+is_num_fullscreen($ws, 1, 'still one fullscreen window');
+is($x->input_focus, $w1->id, 'fullscreen window focused');
+
+
+exit_gracefully($pid);
+
+################################################################################
+# Test popup_during_fullscreen smart
+################################################################################
+
+$config = <<EOT;
+# i3 config file (v4)
+font -misc-fixed-medium-r-normal--13-120-75-75-C-70-iso10646-1
+
+popup_during_fullscreen smart
+EOT
+$pid = launch_with_config($config);
+
+($ws, $w1) = setup;
+
+# Fullscreen stays when transient windows open
+$w2 = open_transient_for($w1);
+is_num_fullscreen($ws, 1, 'still one fullscreen window');
+is($x->input_focus, $w2->id, 'popup focused');
+
+# Fullscreen stays when regular windows open
+open_without_map_wait;
+is_num_fullscreen($ws, 1, 'still one fullscreen window');
+is($x->input_focus, $w2->id, 'popup still focused');
+
+
+exit_gracefully($pid);
+
+done_testing;