diff --git a/lib/facter/custom_facts/core/execution/base.rb b/lib/facter/custom_facts/core/execution/base.rb
index 691637c597..b9e030b9ca 100644
--- a/lib/facter/custom_facts/core/execution/base.rb
+++ b/lib/facter/custom_facts/core/execution/base.rb
@@ -138,9 +138,9 @@ def log_stderr(msg, command, logger)
           logger.debug(format(STDERR_MESSAGE, command, msg.strip))
         end
 
-        def builtin_command?(command)
-          output, _status = Open3.capture2("type #{command}")
-          output.chomp =~ /builtin/ ? true : false
+        # optional function to be defined in subclass if necessary
+        def builtin_command?(_command_)
+          nil
         end
       end
     end
diff --git a/lib/facter/custom_facts/core/execution/posix.rb b/lib/facter/custom_facts/core/execution/posix.rb
index 4208824d99..7f791b5bee 100644
--- a/lib/facter/custom_facts/core/execution/posix.rb
+++ b/lib/facter/custom_facts/core/execution/posix.rb
@@ -11,6 +11,11 @@ def search_paths
           ENV['PATH'].split(File::PATH_SEPARATOR) + DEFAULT_SEARCH_PATHS
         end
 
+        def builtin_command?(command)
+          output, _status = Open3.capture2("type #{command}")
+          output.chomp =~ /builtin/ ? true : false
+        end
+
         def which(bin)
           if absolute_path?(bin)
             return bin if File.executable?(bin) && FileTest.file?(bin)