diff --git a/lib/paperclip/content_type_detector.rb b/lib/paperclip/content_type_detector.rb
index ccab48774..a7508e9b3 100644
--- a/lib/paperclip/content_type_detector.rb
+++ b/lib/paperclip/content_type_detector.rb
@@ -60,7 +60,7 @@ def calculated_type_matches
     end
 
     def type_from_file_contents
-      type_from_mime_magic || type_from_file_command
+      type_from_mime_magic || certificate_type || type_from_file_command
     rescue Errno::ENOENT => e
       Paperclip.log("Error while determining content type: #{e}")
       SENSIBLE_DEFAULT
@@ -75,5 +75,11 @@ def type_from_mime_magic
       @type_from_mime_magic ||=
         MimeMagic.by_magic(File.open(@filename)).try(:type)
     end
+
+    def certificate_type
+      OpenSSL::X509::Certificate.new(File.read(@filename))
+      'application/x-x509-ca-cert'
+    rescue StandardError
+    end
   end
 end