diff --git a/lib/twine/runner.rb b/lib/twine/runner.rb
index fab6d18..bd1aca4 100644
--- a/lib/twine/runner.rb
+++ b/lib/twine/runner.rb
@@ -197,6 +197,7 @@ module Twine
         raise Twine::Error.new("File does not exist: #{@options[:input_path]}")
       end
 
+      error_encountered = false
       Dir.mktmpdir do |temp_dir|
         Zip::File.open(@options[:input_path]) do |zipfile|
           zipfile.each do |entry|
@@ -209,6 +210,7 @@ module Twine
               read_localization_file(real_path)
             rescue Twine::Error => e
               Twine::stderr.puts "#{e.message}"
+              error_encountered = true
             end
           end
         end
@@ -216,6 +218,10 @@ module Twine
 
       output_path = @options[:output_path] || @options[:twine_file]
       write_twine_data(output_path)
+
+      if error_encountered
+        raise Twine::Error.new("At least one file could not be consumed")
+      end
     end
 
     def validate_twine_file
diff --git a/test/fixtures/consume_localization_archive.zip b/test/fixtures/consume_localization_archive.zip
index 5efca14..44619c8 100644
Binary files a/test/fixtures/consume_localization_archive.zip and b/test/fixtures/consume_localization_archive.zip differ
diff --git a/test/test_consume_localization_archive.rb b/test/test_consume_localization_archive.rb
index 21ac4ef..84280b4 100644
--- a/test/test_consume_localization_archive.rb
+++ b/test/test_consume_localization_archive.rb
@@ -4,24 +4,30 @@ class TestConsumeLocalizationArchive < CommandTest
   def setup
     super
 
-    options = {}
-    options[:input_path] = fixture_path 'consume_localization_archive.zip'
-    options[:output_path] = @output_path
-    options[:format] = 'apple'
-
     @twine_file = build_twine_file 'en', 'es' do
       add_section 'Section' do
         add_definition key1: 'value1'
       end
     end
+  end
 
-    @runner = Twine::Runner.new(options, @twine_file)
+  def new_runner(options = {})
+    options[:input_path] = fixture_path 'consume_localization_archive.zip'
+    options[:output_path] = @output_path
+
+    Twine::Runner.new(options, @twine_file)
   end
 
   def test_consumes_zip_file
-    @runner.consume_localization_archive
+    new_runner(format: 'android').consume_localization_archive
 
     assert @twine_file.definitions_by_key['key1'].translations['en'], 'value1-english'
     assert @twine_file.definitions_by_key['key1'].translations['es'], 'value1-spanish'
   end
+
+  def test_raises_error_if_format_ambiguous
+    assert_raises Twine::Error do
+      new_runner.consume_localization_archive
+    end
+  end
 end