diff --git a/CI/circle_parallel.sh b/CI/circle_parallel.sh
index 2ff3aa6b27f..9be0f79cf9c 100755
--- a/CI/circle_parallel.sh
+++ b/CI/circle_parallel.sh
@@ -13,7 +13,7 @@ if [ "$NODE_INDEX" = "1" ]; then
   echo "Running node $NODE_INDEX ..."
   java -version
 
-  sudo apt-get -y install cpanminus
+  sudo apt-get -y install cpanminus libmagic-dev
 
   (cd samples/client/petstore/perl && /bin/bash ./test.bash)
   (cd samples/client/petstore/ruby && mvn integration-test)
diff --git a/modules/openapi-generator/src/main/resources/ruby-client/api_client.mustache b/modules/openapi-generator/src/main/resources/ruby-client/api_client.mustache
index fef2e864c94..19eb7c5cea9 100644
--- a/modules/openapi-generator/src/main/resources/ruby-client/api_client.mustache
+++ b/modules/openapi-generator/src/main/resources/ruby-client/api_client.mustache
@@ -13,6 +13,7 @@ require 'typhoeus'
 {{#isFaraday}}
 require 'faraday'
 require 'faraday/multipart' if Gem::Version.new(Faraday::VERSION) >= Gem::Version.new('2.0')
+require 'filemagic'
 {{/isFaraday}}
 {{#isHttpx}}
 require 'httpx'
diff --git a/modules/openapi-generator/src/main/resources/ruby-client/api_client_faraday_partial.mustache b/modules/openapi-generator/src/main/resources/ruby-client/api_client_faraday_partial.mustache
index 3392e91033d..78452bff0d1 100644
--- a/modules/openapi-generator/src/main/resources/ruby-client/api_client_faraday_partial.mustache
+++ b/modules/openapi-generator/src/main/resources/ruby-client/api_client_faraday_partial.mustache
@@ -94,8 +94,8 @@
         form_params.each do |key, value|
           case value
           when ::File, ::Tempfile
-            # TODO hardcode to application/octet-stream, need better way to detect content type
-            data[key] = Faraday::FilePart.new(value.path, 'application/octet-stream', value.path)
+            filemagic = FileMagic.new(FileMagic::MAGIC_MIME)
+            data[key] = Faraday::FilePart.new(value.path, filemagic.file(value.path, true))
           when ::Array, nil
             # let Faraday handle Array and nil parameters
             data[key] = value
diff --git a/modules/openapi-generator/src/main/resources/ruby-client/gemspec.mustache b/modules/openapi-generator/src/main/resources/ruby-client/gemspec.mustache
index 3e4b613face..b17dce7dc53 100644
--- a/modules/openapi-generator/src/main/resources/ruby-client/gemspec.mustache
+++ b/modules/openapi-generator/src/main/resources/ruby-client/gemspec.mustache
@@ -23,6 +23,7 @@ Gem::Specification.new do |s|
   {{#isFaraday}}
   s.add_runtime_dependency 'faraday', '>= 1.0.1', '< 3.0'
   s.add_runtime_dependency 'faraday-multipart'
+  s.add_runtime_dependency 'ruby-filemagic'
   {{/isFaraday}}
   {{#isTyphoeus}}
   s.add_runtime_dependency 'typhoeus', '~> 1.0', '>= 1.0.1'
diff --git a/samples/client/echo_api/ruby-faraday/lib/openapi_client/api_client.rb b/samples/client/echo_api/ruby-faraday/lib/openapi_client/api_client.rb
index e1b12b0882d..74938757638 100644
--- a/samples/client/echo_api/ruby-faraday/lib/openapi_client/api_client.rb
+++ b/samples/client/echo_api/ruby-faraday/lib/openapi_client/api_client.rb
@@ -17,6 +17,7 @@ require 'tempfile'
 require 'time'
 require 'faraday'
 require 'faraday/multipart' if Gem::Version.new(Faraday::VERSION) >= Gem::Version.new('2.0')
+require 'filemagic'
 
 
 module OpenapiClient
@@ -140,8 +141,8 @@ module OpenapiClient
         form_params.each do |key, value|
           case value
           when ::File, ::Tempfile
-            # TODO hardcode to application/octet-stream, need better way to detect content type
-            data[key] = Faraday::FilePart.new(value.path, 'application/octet-stream', value.path)
+            filemagic = FileMagic.new(FileMagic::MAGIC_MIME)
+            data[key] = Faraday::FilePart.new(value.path, filemagic.file(value.path, true))
           when ::Array, nil
             # let Faraday handle Array and nil parameters
             data[key] = value
diff --git a/samples/client/echo_api/ruby-faraday/openapi_client.gemspec b/samples/client/echo_api/ruby-faraday/openapi_client.gemspec
index 9eaf40366c8..8f99be01f0a 100644
--- a/samples/client/echo_api/ruby-faraday/openapi_client.gemspec
+++ b/samples/client/echo_api/ruby-faraday/openapi_client.gemspec
@@ -30,6 +30,7 @@ Gem::Specification.new do |s|
 
   s.add_runtime_dependency 'faraday', '>= 1.0.1', '< 3.0'
   s.add_runtime_dependency 'faraday-multipart'
+  s.add_runtime_dependency 'ruby-filemagic'
 
   s.add_development_dependency 'rspec', '~> 3.6', '>= 3.6.0'
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/api_client.rb b/samples/client/petstore/ruby-faraday/lib/petstore/api_client.rb
index 59b73ef4c76..89b4fc332e9 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/api_client.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/api_client.rb
@@ -17,6 +17,7 @@ require 'tempfile'
 require 'time'
 require 'faraday'
 require 'faraday/multipart' if Gem::Version.new(Faraday::VERSION) >= Gem::Version.new('2.0')
+require 'filemagic'
 
 
 module Petstore
@@ -140,8 +141,8 @@ module Petstore
         form_params.each do |key, value|
           case value
           when ::File, ::Tempfile
-            # TODO hardcode to application/octet-stream, need better way to detect content type
-            data[key] = Faraday::FilePart.new(value.path, 'application/octet-stream', value.path)
+            filemagic = FileMagic.new(FileMagic::MAGIC_MIME)
+            data[key] = Faraday::FilePart.new(value.path, filemagic.file(value.path, true))
           when ::Array, nil
             # let Faraday handle Array and nil parameters
             data[key] = value
diff --git a/samples/client/petstore/ruby-faraday/petstore.gemspec b/samples/client/petstore/ruby-faraday/petstore.gemspec
index 809f021a710..c9feadd2033 100644
--- a/samples/client/petstore/ruby-faraday/petstore.gemspec
+++ b/samples/client/petstore/ruby-faraday/petstore.gemspec
@@ -30,6 +30,7 @@ Gem::Specification.new do |s|
 
   s.add_runtime_dependency 'faraday', '>= 1.0.1', '< 3.0'
   s.add_runtime_dependency 'faraday-multipart'
+  s.add_runtime_dependency 'ruby-filemagic'
 
   s.add_development_dependency 'rspec', '~> 3.6', '>= 3.6.0'