diff --git a/lib/timecop/time_extensions.rb b/lib/timecop/time_extensions.rb
index f261563..3250c45 100644
--- a/lib/timecop/time_extensions.rb
+++ b/lib/timecop/time_extensions.rb
@@ -58,14 +58,21 @@ def strptime_with_mock_date(str = '-4712-01-01', fmt = '%F', start = Date::ITALY
         Date.new(year, mon, d[:mday], start)
       elsif d[:yday]
         Date.new(year, 1, 1, start).next_day(d[:yday] - 1)
-      elsif d[:cwyear] || d[:cweek] || d[:wnum1] || d[:wday] || d[:cwday]
-        day_of_week_from_monday = if d[:wday]
-                                    (d[:wday] + 6)%7 + 1
-                                  else
-                                    d[:cwday] || 1
-                                  end
-        week = d[:cweek] || d[:wnum1] || now.strftime('%W').to_i
-        Date.commercial(year, week, day_of_week_from_monday, start)
+      elsif d[:cwyear] || d[:cweek] || d[:wnum0] || d[:wnum1] || d[:wday] || d[:cwday]
+        week = d[:cweek] || d[:wnum1] || d[:wnum0] || now.strftime('%W').to_i
+        if d[:wnum0] #Week of year where week starts on sunday
+          if d[:cwday] #monday based day of week
+            Date.strptime_without_mock_date("#{year} #{week} #{d[:cwday]}", '%Y %U %u', start)
+          else
+            Date.strptime_without_mock_date("#{year} #{week} #{d[:wday] || 0}", '%Y %U %w', start)
+          end
+        else #Week of year where week starts on monday
+          if d[:wday] #sunday based day of week
+            Date.strptime_without_mock_date("#{year} #{week} #{d[:wday]}", '%Y %W %w', start)
+          else
+            Date.strptime_without_mock_date("#{year} #{week} #{d[:cwday] || 1}", '%Y %W %u', start)
+          end
+        end
       elsif d[:seconds]
         Time.at(d[:seconds]).to_date
       else
diff --git a/test/date_strptime_scenarios.rb b/test/date_strptime_scenarios.rb
index b7bd19e..de3d619 100644
--- a/test/date_strptime_scenarios.rb
+++ b/test/date_strptime_scenarios.rb
@@ -51,6 +51,10 @@ def test_date_strptime_with_commercial_week_date_and_day_of_week_from_sunday
     assert_equal Date.strptime('1984-09-7', '%G-%V-%u'), Date.new(1984, 3, 04)
   end
 
+  def test_date_strptime_week_number_of_year_day_of_week_sunday_start
+    assert_equal Date.strptime('1984 09 0', '%Y %U %w'), Date.new(1984, 2, 26)
+  end
+
   def test_date_strptime_with_iso_8601_week_date
     assert_equal Date.strptime('1984-W09-1', '%G-W%V-%u'), Date.new(1984, 2, 27)
   end
@@ -124,11 +128,10 @@ def test_strptime_converts_back_and_forth_between_date_and_string_for_many_forma
         '%Y %W %u',
         '%C %y %W %w',
         '%C %y %W %u',
-        #TODO Support these formats
-        # '%Y %U %w',
-        # '%Y %U %u',
-        # '%C %y %U %w',
-        # '%C %y %U %u',
+        '%Y %U %w',
+        '%Y %U %u',
+        '%C %y %U %w',
+        '%C %y %U %u',
       ].each do |fmt|
         s = d.strftime(fmt)
         d2 = Date.strptime(s, fmt)