diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 4957cc4aab4..2a6c60a79ad 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -254,6 +254,7 @@ specs:
     AWS_REGION: us-west-2
     AWS_SECRET_ACCESS_KEY: test
     CAPYBARA_WAIT_TIME_SECONDS: 5
+    RUBYOPT: '--enable=frozen-string-literal'
     COVERAGE: 'true'
     DOCKER_DB_HOST: db-postgres
     POSTGRES_DB: identity_idp_test
diff --git a/spec/bin/aamva-test-cert_spec.rb b/spec/bin/aamva-test-cert_spec.rb
index 12658ac3abc..5a5b604cc47 100644
--- a/spec/bin/aamva-test-cert_spec.rb
+++ b/spec/bin/aamva-test-cert_spec.rb
@@ -16,7 +16,7 @@ def test_cert(auth_url:, verification_url:)
 
   describe '#run' do
     subject(:run) { instance.run(out: out, argv: argv) }
-    let(:out) { StringIO.new('') }
+    let(:out) { StringIO.new(+'') }
     let(:argv) { [] }
 
     context 'missing arguments' do
diff --git a/spec/requests/headers_spec.rb b/spec/requests/headers_spec.rb
index bbf84a83e92..d6dba349a6e 100644
--- a/spec/requests/headers_spec.rb
+++ b/spec/requests/headers_spec.rb
@@ -26,7 +26,7 @@
   end
 
   it 'does not raise an error when HTTP_HOST Header is encoded with ASCII-8BIT' do
-    get root_path, headers: { 'Host' => '¿’¿”'.force_encoding(Encoding::ASCII_8BIT) }
+    get root_path, headers: { 'Host' => (+'¿’¿”').force_encoding(Encoding::ASCII_8BIT) }
 
     expect(response.status).to eq 200
   end
diff --git a/spec/services/barcode_outputter_spec.rb b/spec/services/barcode_outputter_spec.rb
index f0ef078dded..e6a2a0289b9 100644
--- a/spec/services/barcode_outputter_spec.rb
+++ b/spec/services/barcode_outputter_spec.rb
@@ -9,7 +9,7 @@
 
     it 'returns image data' do
       # See: https://en.wikipedia.org/wiki/List_of_file_signatures
-      png_signature = "\x89\x50\x4e\x47\x0d\x0a\x1a\x0a".force_encoding(Encoding::ASCII_8BIT)
+      png_signature = (+"\x89\x50\x4e\x47\x0d\x0a\x1a\x0a").force_encoding(Encoding::ASCII_8BIT)
       expect(image_data).to start_with(png_signature)
     end
   end
diff --git a/spec/services/encrypted_redis_struct_storage_spec.rb b/spec/services/encrypted_redis_struct_storage_spec.rb
index 0841541d3b5..d1db1842fcd 100644
--- a/spec/services/encrypted_redis_struct_storage_spec.rb
+++ b/spec/services/encrypted_redis_struct_storage_spec.rb
@@ -143,7 +143,7 @@ def self.redis_key_prefix
 
       context 'with funky ASCII data inside the struct' do
         let(:data) do
-          "HTTP Status 401 \xE2\x80\x93 Unauthorized".force_encoding('ASCII-8BIT').freeze
+          (+"HTTP Status 401 \xE2\x80\x93 Unauthorized").force_encoding('ASCII-8BIT').freeze
         end
 
         it 'converts the data and stores it' do