diff --git a/plugins/provisioners/chef/config/chef_client.rb b/plugins/provisioners/chef/config/chef_client.rb
index e1585c084..4805310b3 100644
--- a/plugins/provisioners/chef/config/chef_client.rb
+++ b/plugins/provisioners/chef/config/chef_client.rb
@@ -38,10 +38,14 @@ module VagrantPlugins
         def validate(machine)
           errors = _detected_errors
           errors.concat(validate_base(machine))
-          errors << I18n.t("vagrant.config.chef.server_url_empty") if \
-            !chef_server_url || chef_server_url.strip == ""
-          errors << I18n.t("vagrant.config.chef.validation_key_path") if \
-            !validation_key_path
+
+          if chef_server_url.to_s.strip.empty?
+            errors << I18n.t("vagrant.config.chef.server_url_empty")
+          end
+
+          if validation_key_path.to_s.strip.empty?
+            errors << I18n.t("vagrant.config.chef.validation_key_path")
+          end
 
           if delete_client || delete_node
             if !Vagrant::Util::Which.which("knife")