diff --git a/Gemfile.lock b/Gemfile.lock
index 82a614445..97d7f8a3d 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -21,7 +21,7 @@ GEM
       unicode_utils (~> 1.4)
     date_time_precision (0.8.1)
     diff-lcs (1.3)
-    docile (1.3.1)
+    docile (1.3.2)
     ffi (1.10.0)
     formatador (0.2.5)
     guard (2.15.0)
@@ -103,7 +103,7 @@ GEM
     ruby-progressbar (1.10.0)
     ruby_dep (1.5.0)
     shellany (0.0.1)
-    simplecov (0.16.1)
+    simplecov (0.17.0)
       docile (~> 1.1)
       json (>= 1.8, < 3)
       simplecov-html (~> 0.10.0)
@@ -130,7 +130,7 @@ DEPENDENCIES
   rake
   rspec
   rubocop (= 0.67)
-  simplecov
+  simplecov (~> 0.17.0)
   test-unit
 
 RUBY VERSION
diff --git a/fhir_models.gemspec b/fhir_models.gemspec
index a144a7edd..669993b29 100644
--- a/fhir_models.gemspec
+++ b/fhir_models.gemspec
@@ -31,7 +31,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'pry-coolline'
   spec.add_development_dependency 'test-unit'
   spec.add_development_dependency 'rspec'
-  spec.add_development_dependency 'simplecov'
+  spec.add_development_dependency 'simplecov', '~> 0.17.0'
   spec.add_development_dependency 'nokogiri-diff'
   spec.add_development_dependency 'rubocop', '0.67'
   spec.add_development_dependency 'codeclimate-test-reporter'