diff --git a/lib/shoulda/matchers/util.rb b/lib/shoulda/matchers/util.rb
index 46d512637..771fb1daa 100644
--- a/lib/shoulda/matchers/util.rb
+++ b/lib/shoulda/matchers/util.rb
@@ -94,7 +94,7 @@ def self.dummy_value_for(column_type, array: false)
             0
           when :date
             Date.new(2100, 1, 1)
-          when :datetime, :timestamp
+          when :datetime, :timestamp, :timestamptz
             DateTime.new(2100, 1, 1)
           when :time
             Time.new(2000, 1, 1)
diff --git a/spec/unit/shoulda/matchers/active_record/validate_uniqueness_of_matcher_spec.rb b/spec/unit/shoulda/matchers/active_record/validate_uniqueness_of_matcher_spec.rb
index 53746de42..68886a128 100644
--- a/spec/unit/shoulda/matchers/active_record/validate_uniqueness_of_matcher_spec.rb
+++ b/spec/unit/shoulda/matchers/active_record/validate_uniqueness_of_matcher_spec.rb
@@ -829,6 +829,16 @@
         column_type: :datetime
     end
 
+    context 'when one of the scoped attributes is a timestamp column (using DateTime)' do
+      include_context 'it supports scoped attributes of a certain type',
+        column_type: :timestamp
+    end
+
+    context 'when one of the scoped attributes is a timestamp with time zone column (using DateTime)' do
+      include_context 'it supports scoped attributes of a certain type',
+        column_type: :timestamptz
+    end
+
     context 'when one of the scoped attributes is a time column (using Time)' do
       include_context 'it supports scoped attributes of a certain type',
         column_type: :time