diff --git a/Gemfile.lock b/Gemfile.lock
index a12dcdfe..f42dd673 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -3,6 +3,7 @@ PATH
   specs:
     cocina-models (0.99.1)
       activesupport
+      commonmarker (= 2.0.1)
       deprecation
       dry-struct (~> 1.0)
       dry-types (~> 1.1)
@@ -43,7 +44,7 @@ GEM
       json_schema (~> 0.14, >= 0.14.3)
       openapi_parser (~> 1.0)
       rack (>= 1.5)
-    commonmarker (2.0.2)
+    commonmarker (2.0.1)
       rb_sys (~> 0.9)
     concurrent-ruby (1.3.4)
     connection_pool (2.4.1)
diff --git a/cocina-models.gemspec b/cocina-models.gemspec
index 5ba96501..229250ff 100644
--- a/cocina-models.gemspec
+++ b/cocina-models.gemspec
@@ -25,6 +25,7 @@ Gem::Specification.new do |spec|
   spec.required_ruby_version = '>= 3.0'
 
   spec.add_dependency 'activesupport'
+  spec.add_dependency 'commonmarker', '2.0.1' # There is a breaking change in 2.0.2 with openapi3_parser
   spec.add_dependency 'deprecation'
   spec.add_dependency 'dry-struct', '~> 1.0'
   spec.add_dependency 'dry-types', '~> 1.1'