diff --git a/lib/ruby_maven.rb b/lib/ruby_maven.rb
index 66ba27c..e977878 100644
--- a/lib/ruby_maven.rb
+++ b/lib/ruby_maven.rb
@@ -78,7 +78,7 @@ def self.launch( *args )
         # ruby maven defines the polyglot version and this jar sets up its classpath
         # i.e. on upgrade or downgrade the right version will be picked
         FileUtils.cp(source, File.join(ext_dir, jar.sub(/-[0-9.]*(-SNAPSHOT)?.jar$/, '.jar')))
-      elsif not File.exists?(File.join(ext_dir, jar)) and not jar =~ /jruby-(core|stdlib).*/
+      elsif not File.exist?(File.join(ext_dir, jar)) and not jar =~ /jruby-(core|stdlib).*/
         # jar files are immutable as they carry the version
         warn jar
         FileUtils.cp(source, File.join(ext_dir, jar.sub(/-9.4.5.0/, '')))