diff --git a/Gemfile.lock b/Gemfile.lock
index f0039b2..4d81a4b 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -9,7 +9,7 @@ GEM
     docile (1.1.5)
     json (2.0.2)
     power_assert (0.3.0)
-    rake (11.2.2)
+    rake (12.3.3)
     simplecov (0.12.0)
       docile (~> 1.1.0)
       json (>= 1.8, < 3)
@@ -23,7 +23,7 @@ PLATFORMS
 
 DEPENDENCIES
   chartd!
-  rake (~> 11.2)
+  rake (~> 12.3)
   simplecov (~> 0.12)
   test-unit (~> 3.2)
 
diff --git a/chartd.gemspec b/chartd.gemspec
index 97d1d57..770e93a 100644
--- a/chartd.gemspec
+++ b/chartd.gemspec
@@ -11,7 +11,7 @@ Gem::Specification.new do |s|
   s.homepage    = 'https://github.com/commissure/chartd-rb'
   s.license     = 'MIT'
 
-  s.add_development_dependency 'rake', '~> 11.2'
+  s.add_development_dependency 'rake', '~> 12.3'
   s.add_development_dependency 'test-unit', '~> 3.2'
   s.add_development_dependency 'simplecov', '~> 0.12'
 end