diff --git a/lib/active_model/serializer/concerns/caching.rb b/lib/active_model/serializer/concerns/caching.rb
index 35bd8e64..7b3ff37e 100644
--- a/lib/active_model/serializer/concerns/caching.rb
+++ b/lib/active_model/serializer/concerns/caching.rb
@@ -56,7 +56,7 @@ module ActiveModel
         def digest_caller_file(caller_line)
           serializer_file_path = caller_line[CALLER_FILE]
           serializer_file_contents = IO.read(serializer_file_path)
-          Digest::MD5.hexdigest(serializer_file_contents)
+          Digest::SHA1.hexdigest(serializer_file_contents)
         rescue TypeError, Errno::ENOENT
           warn <<-EOF.strip_heredoc
             Cannot digest non-existent file: '#{caller_line}'.
diff --git a/test/cache_test.rb b/test/cache_test.rb
index fdab362a..f67f98a6 100644
--- a/test/cache_test.rb
+++ b/test/cache_test.rb
@@ -447,13 +447,13 @@ module ActiveModelSerializers
 
     def test_uses_file_digest_in_cache_key
       render_object_with_cache(@blog)
-      file_digest = Digest::MD5.hexdigest(File.open(__FILE__).read)
+      file_digest = Digest::SHA1.hexdigest(File.open(__FILE__).read)
       key = "#{@blog.cache_key}/#{adapter.cache_key}/#{file_digest}"
       assert_equal(@blog_serializer.attributes, cache_store.fetch(key))
     end
 
     def test_cache_digest_definition
-      file_digest = Digest::MD5.hexdigest(File.open(__FILE__).read)
+      file_digest = Digest::SHA1.hexdigest(File.open(__FILE__).read)
       assert_equal(file_digest, @post_serializer.class._cache_digest)
     end
 
@@ -560,7 +560,7 @@ module ActiveModelSerializers
       path = file.path
       caller_line = "#{path}:1:in `<top (required)>'"
       file.close
-      assert_equal ActiveModel::Serializer.digest_caller_file(caller_line), Digest::MD5.hexdigest(contents)
+      assert_equal ActiveModel::Serializer.digest_caller_file(caller_line), Digest::SHA1.hexdigest(contents)
     ensure
       file.unlink
       FileUtils.remove_entry dir