diff --git a/mrbgem.rake b/mrbgem.rake
index f57d8ade8..c59305709 100644
--- a/mrbgem.rake
+++ b/mrbgem.rake
@@ -2,7 +2,6 @@ MRuby::Gem::Specification.new('mruby-set') do |spec|
   spec.license = 'MIT'
   spec.authors = 'yui-knk'
 
-  spec.add_dependency "mruby-sprintf", :core => "mruby-sprintf"
   spec.add_dependency "mruby-hash-ext", :core => "mruby-hash-ext"
   spec.add_dependency "mruby-enumerator", :core => "mruby-enumerator"
 end
diff --git a/mrblib/mrb_set.rb b/mrblib/mrb_set.rb
index 4db9729ff..dbf77b93c 100644
--- a/mrblib/mrb_set.rb
+++ b/mrblib/mrb_set.rb
@@ -307,7 +307,7 @@ class Set
   end
 
   def inspect
-    sprintf('#<%s: {%s}>', self.class, to_a.inspect[1..-2])
+    "#<#{self.class}: {#{self.to_a.inspect[1..-2]}}>"
   end
 
 end