diff --git a/config/boot_settings.rb b/config/boot_settings.rb
index c5665ccdf15..143cfc20655 100644
--- a/config/boot_settings.rb
+++ b/config/boot_settings.rb
@@ -5,6 +5,7 @@
 SETTINGS = File.exist?(dist_settings_file) ? YAML.load(ERB.new(File.read(dist_settings_file)).result) || {} : {}
 
 settings_file = File.expand_path('../settings.yaml', __FILE__)
-SETTINGS[:rails] = YAML.load(ERB.new(File.read(settings_file)).result)[:rails]
+settings = YAML.load(ERB.new(File.read(settings_file)).result)
+SETTINGS[:rails] = settings[:rails] if settings[:rails]
 SETTINGS[:rails] ||= RUBY_VERSION < '2.3' ? '4.2' : '5.0'
 SETTINGS[:rails] = '%.1f' % SETTINGS[:rails] if SETTINGS[:rails].is_a?(Float) # unquoted YAML value