diff --git a/lib/carrierwave/sanitized_file.rb b/lib/carrierwave/sanitized_file.rb
index fd5d3a378..8043e80eb 100644
--- a/lib/carrierwave/sanitized_file.rb
+++ b/lib/carrierwave/sanitized_file.rb
@@ -2,6 +2,7 @@
 require 'active_support/core_ext/string/multibyte'
 require 'mini_mime'
 require 'mimemagic'
+require 'mimemagic/overlay'
 
 module CarrierWave
 
diff --git a/spec/fixtures/resume.docx b/spec/fixtures/resume.docx
new file mode 100644
index 000000000..a7308a366
Binary files /dev/null and b/spec/fixtures/resume.docx differ
diff --git a/spec/fixtures/slidedeck.pptx b/spec/fixtures/slidedeck.pptx
new file mode 100644
index 000000000..9a0b22748
Binary files /dev/null and b/spec/fixtures/slidedeck.pptx differ
diff --git a/spec/sanitized_file_spec.rb b/spec/sanitized_file_spec.rb
index 70298776d..20fb607f5 100644
--- a/spec/sanitized_file_spec.rb
+++ b/spec/sanitized_file_spec.rb
@@ -195,6 +195,26 @@
       expect(sanitized_file.content_type).to eq("application/msword")
     end
 
+    it "handles Mime::Type of docx" do
+      file = File.open(file_path('resume.docx'))
+
+      sanitized_file = CarrierWave::SanitizedFile.new(file)
+      allow(sanitized_file).to receive(:file).and_return(file)
+
+      expect { sanitized_file.content_type }.not_to raise_error
+      expect(sanitized_file.content_type).to eq("application/vnd.openxmlformats-officedocument.wordprocessingml.document")
+    end
+
+    it "handles Mime::Type of pptx" do
+      file = File.open(file_path('slidedeck.pptx'))
+
+      sanitized_file = CarrierWave::SanitizedFile.new(file)
+      allow(sanitized_file).to receive(:file).and_return(file)
+
+      expect { sanitized_file.content_type }.not_to raise_error
+      expect(sanitized_file.content_type).to eq("application/vnd.openxmlformats-officedocument.presentationml.presentation")
+    end
+
     it "reads content type from path if missing" do
       sanitized_file = CarrierWave::SanitizedFile.new("llama.jpg")