diff --git a/Gemfile b/Gemfile
index 5ed72b7..628e90b 100644
--- a/Gemfile
+++ b/Gemfile
@@ -3,7 +3,7 @@ source 'https://rubygems.org'
 gem "json"
 gem "rspec"
 gem "rake"
-gem "simplecov"
+gem "simplecov", "~> 0.15.0"
 gem "yard"
 gem "rdoc"
 gem "redcarpet"
diff --git a/Gemfile.lock b/Gemfile.lock
index 421c32c..e0f582f 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -20,7 +20,7 @@ GEM
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.9.0)
     rspec-support (3.9.2)
-    simplecov (0.15.0)
+    simplecov (0.15.1)
       docile (~> 1.1.0)
       json (>= 1.8, < 3)
       simplecov-html (~> 0.10.0)
@@ -38,7 +38,7 @@ DEPENDENCIES
   rdoc
   redcarpet
   rspec
-  simplecov
+  simplecov (~> 0.15.0)
   syntax
   yard