diff --git a/editor/editor_tests/opening_hours_ui_test.cpp b/editor/editor_tests/opening_hours_ui_test.cpp
index 212263b338..b851526ceb 100644
--- a/editor/editor_tests/opening_hours_ui_test.cpp
+++ b/editor/editor_tests/opening_hours_ui_test.cpp
@@ -202,4 +202,23 @@ UNIT_TEST(TestAppendTimeTable)
 
     TEST(!tts.GetComplementTimeTable().IsValid(), ());
   }
+  {
+    TimeTableSet tts;
+    auto tt = tts.GetComplementTimeTable();
+    tt.AddWorkingDay(osmoh::Weekday::Friday);
+
+    TEST(tts.Append(tt), ());
+
+    TEST_EQUAL(tts.size(), 2, ());
+    TEST_EQUAL(tts.front().GetWorkingDays().size(), 6, ());
+    TEST_EQUAL(tts.back().GetWorkingDays().size(), 1, ());
+
+    TEST(!tts.GetComplementTimeTable().IsValid(), ());
+
+    tt = tts[0];
+    tt.AddWorkingDay(osmoh::Weekday::Friday);
+    TEST(!tts.Append(tt), ());
+    TEST_EQUAL(tts.front().GetWorkingDays().size(), 6, ());
+    TEST_EQUAL(tts.back().GetWorkingDays().size(), 1, ());
+  }
 }
diff --git a/editor/opening_hours_ui.cpp b/editor/opening_hours_ui.cpp
index 1868b081ec..f0984b5874 100644
--- a/editor/opening_hours_ui.cpp
+++ b/editor/opening_hours_ui.cpp
@@ -150,7 +150,7 @@ TimeTable TimeTable::GetPredefinedTimeTable()
 bool TimeTable::SetWorkingDays(TOpeningDays const & days)
 {
   if (days.empty())
-    return true;
+    return false;
   m_weekdays = days;
   return true;
 }