diff --git a/main.go b/main.go
index 204dcf0..a4f3177 100644
--- a/main.go
+++ b/main.go
@@ -31,6 +31,8 @@ func (m *rbiModule) InitContext(c pgs.BuildContext) {
 
 	funcs := map[string]interface{}{
 		"increment":                m.increment,
+		"optional":                 m.optional,
+		"optionalOneOf":            m.optionalOneOf,
 		"willGenerateInvalidRuby":  m.willGenerateInvalidRuby,
 		"rubyModules":              ruby_types.RubyModules,
 		"rubyPackage":              ruby_types.RubyPackage,
@@ -79,6 +81,14 @@ func (m *rbiModule) increment(i int) int {
 	return i + 1
 }
 
+func (m *rbiModule) optional(field pgs.Field) bool {
+	return field.Descriptor().GetProto3Optional()
+}
+
+func (m *rbiModule) optionalOneOf(oneOf pgs.OneOf) bool {
+	return len(oneOf.Fields()) == 1 && oneOf.Fields()[0].Descriptor().GetProto3Optional()
+}
+
 func (m *rbiModule) willGenerateInvalidRuby(fields []pgs.Field) bool {
 	for _, field := range fields {
 		if !validRubyField.MatchString(string(field.Name())) {
@@ -141,7 +151,15 @@ class {{ rubyMessageType . }}
     {{ .Name }}: {{ rubyFieldValue . }}{{ end }}
   )
   end
-{{ end }}{{ range .Fields }}
+{{ end }}{{ range .Fields }}{{ if optional . }}
+  sig { returns(T::Boolean) }
+  def has_{{ .Name }}?
+  end
+
+  sig { void }
+  def clear_{{ .Name }}
+  end
+{{ end }}
   sig { returns({{ rubyGetterFieldType . }}) }
   def {{ .Name }}
   end
@@ -149,11 +167,11 @@ class {{ rubyMessageType . }}
   sig { params(value: {{ rubySetterFieldType . }}).void }
   def {{ .Name }}=(value)
   end
-{{ end }}{{ range .OneOfs }}
+{{ end }}{{ range .OneOfs }}{{ if not (optionalOneOf .) }}
   sig { returns(T.nilable(Symbol)) }
   def {{ .Name }}
   end
-{{ end }}
+{{ end }}{{ end }}
   sig { params(field: String).returns(T.untyped) }
   def [](field)
   end
diff --git a/testdata/subdir/messages.proto b/testdata/subdir/messages.proto
index 9ec1d97..65a29b1 100644
--- a/testdata/subdir/messages.proto
+++ b/testdata/subdir/messages.proto
@@ -72,4 +72,6 @@ message AllTypes {
   map<string, IntegerMessage> string_map_value = 26;
   map<int32, IntegerMessage> int32_map_value = 27;
   map<string, Corpus> enum_map_value = 28;
+
+  optional bool optional_bool = 29;
 }
diff --git a/testdata/subdir/messages_pb.rb b/testdata/subdir/messages_pb.rb
index 5716f1a..607c315 100644
--- a/testdata/subdir/messages_pb.rb
+++ b/testdata/subdir/messages_pb.rb
@@ -42,6 +42,7 @@
       map :string_map_value, :string, :message, 26, "testdata.subdir.IntegerMessage"
       map :int32_map_value, :int32, :message, 27, "testdata.subdir.IntegerMessage"
       map :enum_map_value, :string, :enum, 28, "testdata.subdir.AllTypes.Corpus"
+      proto3_optional :optional_bool, :bool, 29
       oneof :test_oneof do
         optional :name, :string, 24
         optional :sub_message, :bool, 25
diff --git a/testdata/subdir/messages_pb.rbi b/testdata/subdir/messages_pb.rbi
index eb28893..e72485c 100644
--- a/testdata/subdir/messages_pb.rbi
+++ b/testdata/subdir/messages_pb.rbi
@@ -150,7 +150,8 @@ class Testdata::Subdir::AllTypes
       sub_message: T.nilable(T::Boolean),
       string_map_value: T.nilable(T::Hash[String, T.nilable(Testdata::Subdir::IntegerMessage)]),
       int32_map_value: T.nilable(T::Hash[Integer, T.nilable(Testdata::Subdir::IntegerMessage)]),
-      enum_map_value: T.nilable(T::Hash[String, T.any(Symbol, String, Integer)])
+      enum_map_value: T.nilable(T::Hash[String, T.any(Symbol, String, Integer)]),
+      optional_bool: T.nilable(T::Boolean)
     ).void
   end
   def initialize(
@@ -181,7 +182,8 @@ class Testdata::Subdir::AllTypes
     sub_message: false,
     string_map_value: Google::Protobuf::Map.new(:string, :message, Testdata::Subdir::IntegerMessage),
     int32_map_value: Google::Protobuf::Map.new(:int32, :message, Testdata::Subdir::IntegerMessage),
-    enum_map_value: Google::Protobuf::Map.new(:string, :enum)
+    enum_map_value: Google::Protobuf::Map.new(:string, :enum),
+    optional_bool: false
   )
   end
 
@@ -409,6 +411,22 @@ class Testdata::Subdir::AllTypes
   def enum_map_value=(value)
   end
 
+  sig { returns(T::Boolean) }
+  def has_optional_bool?
+  end
+
+  sig { void }
+  def clear_optional_bool
+  end
+
+  sig { returns(T::Boolean) }
+  def optional_bool
+  end
+
+  sig { params(value: T::Boolean).void }
+  def optional_bool=(value)
+  end
+
   sig { returns(T.nilable(Symbol)) }
   def test_oneof
   end