diff --git a/.gitignore b/.gitignore
index 1de1f46a..77144cac 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,7 @@
 pkg
 tmp
 .DS_Store
+coverage/
 
 *.bundle
 *.o
diff --git a/Gemfile.lock b/Gemfile.lock
index fe8981b6..4f26b32a 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -9,6 +9,7 @@ GEM
   specs:
     ast (2.4.1)
     diff-lcs (1.5.0)
+    docile (1.4.0)
     google-protobuf (3.23.4)
     parallel (1.20.1)
     parser (2.7.2.0)
@@ -42,6 +43,12 @@ GEM
     rubocop-rspec (1.15.1)
       rubocop (>= 0.42.0)
     ruby-progressbar (1.10.1)
+    simplecov (0.22.0)
+      docile (~> 1.1)
+      simplecov-html (~> 0.11)
+      simplecov_json_formatter (~> 0.1)
+    simplecov-html (0.12.3)
+    simplecov_json_formatter (0.1.4)
     unicode-display_width (1.7.0)
 
 PLATFORMS
@@ -53,6 +60,7 @@ DEPENDENCIES
   rspec (~> 3.0)
   rubocop (= 0.49.1)
   rubocop-rspec (= 1.15.1)
+  simplecov (~> 0)
 
 BUNDLED WITH
    2.3.26
diff --git a/pg_query.gemspec b/pg_query.gemspec
index 6d28a5df..dcb8126b 100644
--- a/pg_query.gemspec
+++ b/pg_query.gemspec
@@ -25,5 +25,6 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'rspec', '~> 3.0'
   s.add_development_dependency 'rubocop', '0.49.1'
   s.add_development_dependency 'rubocop-rspec', '1.15.1'
+  s.add_development_dependency 'simplecov', '~> 0'
   s.add_dependency 'google-protobuf', '>= 3.22.3'
 end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index e6013571..c9fa88e8 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1 +1,7 @@
+require 'simplecov'
+
+SimpleCov.start do
+  add_filter '/spec/'
+end
+
 require 'pg_query'