diff --git a/lib/i18n/locale/fallbacks.rb b/lib/i18n/locale/fallbacks.rb
index a8f8b3e0..e30acc43 100644
--- a/lib/i18n/locale/fallbacks.rb
+++ b/lib/i18n/locale/fallbacks.rb
@@ -74,7 +74,6 @@ def map(*args, &block)
               @map[from] << _to.to_sym
             end
           end
-          replace @map
         else
           @map.map(*args, &block)
         end
diff --git a/lib/i18n/tests/localization/date.rb b/lib/i18n/tests/localization/date.rb
index c06b7ece..c21fbbf3 100644
--- a/lib/i18n/tests/localization/date.rb
+++ b/lib/i18n/tests/localization/date.rb
@@ -64,7 +64,7 @@ def setup
         end
 
         test "localize Date: given missing translations it returns the correct error message" do
-          assert_equal 'translation missing: fr.date.abbr_month_names', I18n.l(@date, :format => '%b', :locale => :fr)
+          assert_equal 'Translation missing: fr.date.abbr_month_names', I18n.l(@date, :format => '%b', :locale => :fr)
         end
 
         test "localize Date: given an unknown format it does not fail" do
diff --git a/lib/i18n/tests/localization/date_time.rb b/lib/i18n/tests/localization/date_time.rb
index b09b8880..b5d3527d 100644
--- a/lib/i18n/tests/localization/date_time.rb
+++ b/lib/i18n/tests/localization/date_time.rb
@@ -60,7 +60,7 @@ def setup
         end
 
         test "localize DateTime: given missing translations it returns the correct error message" do
-          assert_equal 'translation missing: fr.date.abbr_month_names', I18n.l(@datetime, :format => '%b', :locale => :fr)
+          assert_equal 'Translation missing: fr.date.abbr_month_names', I18n.l(@datetime, :format => '%b', :locale => :fr)
         end
 
         test "localize DateTime: given a meridian indicator format it returns the correct meridian indicator" do
diff --git a/lib/i18n/tests/localization/time.rb b/lib/i18n/tests/localization/time.rb
index 7afe176f..456a7602 100644
--- a/lib/i18n/tests/localization/time.rb
+++ b/lib/i18n/tests/localization/time.rb
@@ -61,7 +61,7 @@ def setup
         end
 
         test "localize Time: given missing translations it returns the correct error message" do
-          assert_equal 'translation missing: fr.date.abbr_month_names', I18n.l(@time, :format => '%b', :locale => :fr)
+          assert_equal 'Translation missing: fr.date.abbr_month_names', I18n.l(@time, :format => '%b', :locale => :fr)
         end
 
         test "localize Time: given a meridian indicator format it returns the correct meridian indicator" do
diff --git a/lib/i18n/tests/lookup.rb b/lib/i18n/tests/lookup.rb
index 3bd46b8b..bbd775f0 100644
--- a/lib/i18n/tests/lookup.rb
+++ b/lib/i18n/tests/lookup.rb
@@ -30,7 +30,7 @@ def setup
       end
 
       test "lookup: given a missing key, no default and no raise option it returns an error message" do
-        assert_equal "translation missing: en.missing", I18n.t(:missing)
+        assert_equal "Translation missing: en.missing", I18n.t(:missing)
       end
 
       test "lookup: given a missing key, no default and the raise option it raises MissingTranslationData" do
diff --git a/test/backend/exceptions_test.rb b/test/backend/exceptions_test.rb
index cc221669..e19c8121 100644
--- a/test/backend/exceptions_test.rb
+++ b/test/backend/exceptions_test.rb
@@ -10,7 +10,7 @@ def setup
     exception = catch(:exception) do
       I18n.t(:'baz.missing', :scope => :'foo.bar', :throw => true)
     end
-    assert_equal "translation missing: en.foo.bar.baz.missing", exception.message
+    assert_equal "Translation missing: en.foo.bar.baz.missing", exception.message
   end
 
   test "exceptions: MissingTranslationData message from #translate includes the given scope and full key" do
@@ -18,7 +18,7 @@ def setup
       I18n.t(:'baz.missing', :scope => :'foo.bar', :raise => true)
     rescue I18n::MissingTranslationData => exception
     end
-    assert_equal "translation missing: en.foo.bar.baz.missing", exception.message
+    assert_equal "Translation missing: en.foo.bar.baz.missing", exception.message
   end
 
   test "exceptions: MissingTranslationData message from #localize includes the given scope and full key" do
@@ -26,7 +26,7 @@ def setup
       I18n.l(Time.now, :format => :foo)
     rescue I18n::MissingTranslationData => exception
     end
-    assert_equal "translation missing: en.time.formats.foo", exception.message
+    assert_equal "Translation missing: en.time.formats.foo", exception.message
   end
 
   test "exceptions: MissingInterpolationArgument message includes missing key, provided keys and full string" do
diff --git a/test/backend/fallbacks_test.rb b/test/backend/fallbacks_test.rb
index 742db2e6..6d61408f 100644
--- a/test/backend/fallbacks_test.rb
+++ b/test/backend/fallbacks_test.rb
@@ -60,8 +60,14 @@ def setup
     assert_nil I18n.t(:missing_bar, :locale => :'de-DE', :default => nil)
   end
 
-  test "returns the translation missing message if the default is also missing" do
-    assert_equal 'translation missing: de-DE.missing_bar', I18n.t(:missing_bar, :locale => :'de-DE', :default => [:missing_baz])
+  test "returns the Translation missing: message if the default is also missing" do
+    translation_missing_message = <<~MSG
+      Translation missing. Options considered were:
+      - de-DE.missing_bar
+      - de-DE.missing_baz
+    MSG
+
+    assert_equal translation_missing_message.chomp, I18n.t(:missing_bar, :locale => :'de-DE', :default => [:missing_baz])
   end
 
   test "returns the :'de-DE' default :baz translation for a missing :'de-DE' when defaults contains Symbol" do
diff --git a/test/backend/key_value_test.rb b/test/backend/key_value_test.rb
index aefa9ce6..34bce7b0 100644
--- a/test/backend/key_value_test.rb
+++ b/test/backend/key_value_test.rb
@@ -21,7 +21,7 @@ def assert_flattens(expected, nested, escape=true, subtree=true)
     assert_flattens({:"a.b"=>['a', 'b']}, {:a=>{:b =>['a', 'b']}}, true, false)
     assert_flattens({:"a.b" => "c"}, {:"a.b" => "c"}, false)
   end
-  
+
   test "store_translations supports numeric keys" do
     setup_backend!
     store_translations(:en, 1 => 'foo')
@@ -60,8 +60,8 @@ def assert_flattens(expected, nested, escape=true, subtree=true)
     I18n.backend.send(:translations)
     expected = { :en => {:foo => { :bar => 'bar', :baz => 'baz' }} }
     assert_equal expected, translations
-  end 
-  
+  end
+
   test "subtrees enabled: given incomplete pluralization data it raises I18n::InvalidPluralizationData" do
     setup_backend!
     store_translations(:en, :bar => { :one => "One" })
@@ -71,7 +71,7 @@ def assert_flattens(expected, nested, escape=true, subtree=true)
   test "subtrees disabled: given incomplete pluralization data it returns an error message" do
     setup_backend!(false)
     store_translations(:en, :bar => { :one => "One" })
-    assert_equal "translation missing: en.bar", I18n.t(:bar, :count => 2)
+    assert_equal "Translation missing: en.bar", I18n.t(:bar, :count => 2)
   end
 
   test "translate handles subtrees for pluralization" do
@@ -79,7 +79,7 @@ def assert_flattens(expected, nested, escape=true, subtree=true)
     store_translations(:en, :bar => { :one => "One" })
     assert_equal("One", I18n.t("bar", :count => 1))
   end
-  
+
   test "subtrees enabled: returns localized string given missing pluralization data" do
     setup_backend!(true)
     assert_equal 'bar', I18n.t("foo.bar", count: 1)
@@ -89,7 +89,7 @@ def assert_flattens(expected, nested, escape=true, subtree=true)
     setup_backend!(false)
     assert_equal 'bar', I18n.t("foo.bar", count: 1)
   end
-  
+
   test "subtrees enabled: Returns fallback default given missing pluralization data" do
     setup_backend!(true)
     I18n.backend.extend I18n::Backend::Fallbacks
diff --git a/test/i18n/exceptions_test.rb b/test/i18n/exceptions_test.rb
index 3920bf91..771308d0 100644
--- a/test/i18n/exceptions_test.rb
+++ b/test/i18n/exceptions_test.rb
@@ -32,12 +32,6 @@ def test_invalid_locale_stores_locale
     end
   end
 
-  test "MissingTranslationData message contains all potential options" do
-    force_missing_translation_data(default: [:option_a, :option_b]) do |exception|
-      assert_equal "translation missing. Options considered were:\n- de.bar.option_a, \n- de.bar.option_a", exception.message
-    end
-  end
-
   test "InvalidPluralizationData stores entry, count and key" do
     force_invalid_pluralization_data do |exception|
       assert_equal({:other => "bar"}, exception.entry)
diff --git a/test/i18n_test.rb b/test/i18n_test.rb
index 058d2c03..3f576fb8 100644
--- a/test/i18n_test.rb
+++ b/test/i18n_test.rb
@@ -209,16 +209,16 @@ def setup
   end
 
   # def test_translate_given_no_args_raises_missing_translation_data
-  #   assert_equal "translation missing: en, no key", I18n.t
+  #   assert_equal "Translation missing: en, no key", I18n.t
   # end
 
   test "translate given a bogus key returns an error message" do
-    assert_equal "translation missing: en.bogus", I18n.t(:bogus)
+    assert_equal "Translation missing: en.bogus", I18n.t(:bogus)
   end
 
   test "translate given multiple bogus keys returns an array of error messages" do
     assert_equal(
-      ["translation missing: en.bogus", "translation missing: en.also_bogus"],
+      ["Translation missing: en.bogus", "Translation missing: en.also_bogus"],
       I18n.t([:bogus, :also_bogus]),
     )
   end
@@ -266,7 +266,7 @@ def setup
         I18n.t('foo')
       end
 
-      assert_equal 'translation missing: en.foo', I18n.t('foo', locale: :en)
+      assert_equal 'Translation missing: en.foo', I18n.t('foo', locale: :en)
     end
   end