diff --git a/lib/protoboeuf/codegen.rb b/lib/protoboeuf/codegen.rb
index f553029..b28ebcc 100644
--- a/lib/protoboeuf/codegen.rb
+++ b/lib/protoboeuf/codegen.rb
@@ -2,7 +2,7 @@
 
 require "erb"
 require "syntax_tree"
-require_relative "codegen_type_helper"
+require_relative "type_helper"
 
 module ProtoBoeuf
   class CodeGen
diff --git a/lib/protoboeuf/codegen_type_helper.rb b/lib/protoboeuf/codegen_type_helper.rb
deleted file mode 100644
index b3ef6dd..0000000
--- a/lib/protoboeuf/codegen_type_helper.rb
+++ /dev/null
@@ -1,106 +0,0 @@
-# frozen_string_literal: true
-
-module ProtoBoeuf
-  class CodeGen
-    module TypeHelper
-      TYPE_MAPPING = {
-        :TYPE_INT32 => "Integer",
-        :TYPE_SINT32 => "Integer",
-        :TYPE_UINT32 => "Integer",
-        :TYPE_INT64 => "Integer",
-        :TYPE_SINT64 => "Integer",
-        :TYPE_FIXED64 => "Integer",
-        :TYPE_SFIXED64 => "Integer",
-        :TYPE_FIXED32 => "Integer",
-        :TYPE_SFIXED32 => "Integer",
-        :TYPE_UINT64 => "Integer",
-        :TYPE_STRING => "String",
-        :TYPE_DOUBLE => "Float",
-        :TYPE_FLOAT => "Float",
-        :TYPE_BYTES => "String",
-        :TYPE_ENUM => "Symbol",
-        "google.protobuf.BoolValue" => "ProtoBoeuf::Protobuf::BoolValue",
-        "google.protobuf.Int32Value" => "ProtoBoeuf::Protobuf::Int32Value",
-        "google.protobuf.Int64Value" => "ProtoBoeuf::Protobuf::Int64Value",
-        "google.protobuf.UInt32Value" => "ProtoBoeuf::Protobuf::UInt32Value",
-        "google.protobuf.UInt64Value" => "ProtoBoeuf::Protobuf::UInt64Value",
-        "google.protobuf.FloatValue" => "ProtoBoeuf::Protobuf::FloatValue",
-        "google.protobuf.DoubleValue" => "ProtoBoeuf::Protobuf::DoubleValue",
-        "google.protobuf.StringValue" => "ProtoBoeuf::Protobuf::StringValue",
-        "google.protobuf.BytesValue" => "ProtoBoeuf::Protobuf::BytesValue",
-        "google.protobuf.Timestamp" => "ProtoBoeuf::Protobuf::Timestamp",
-      }.freeze
-
-      def type_signature(params: nil, returns: nil, newline: false)
-        return "" unless generate_types
-
-        sig = []
-        sig << "params(#{params.map { |k, v| "#{k}: #{convert_type(v)}" }.join(", ")})" if params
-        sig << "returns(#{returns})" if returns
-        sig << "void" unless returns
-
-        complete_sig = "sig { #{sig.join(".")} }"
-        complete_sig += "\n" if newline
-
-        complete_sig
-      end
-
-      def initialize_type_signature(fields)
-        return "" unless generate_types
-
-        type_signature(params: fields_to_params(fields), newline: true)
-      end
-
-      def reader_type_signature(field)
-        type_signature(returns: convert_field_type(field))
-      end
-
-      def extend_t_sig
-        return "" unless generate_types
-
-        "extend T::Sig"
-      end
-
-      private
-
-      def convert_type(converted_type, optional: false, array: false)
-        converted_type = "T::Array[#{converted_type}]" if array
-        converted_type = "T.nilable(#{converted_type})" if optional
-        converted_type
-      end
-
-      def convert_field_type(field)
-        converted_type = if map_field?(field)
-          map_type = self.map_type(field)
-          "T::Hash[#{convert_field_type(map_type.field[0])}, #{convert_field_type(map_type.field[1])}]"
-        else
-          case field.type
-          when :TYPE_BOOL
-            "T::Boolean"
-          when :TYPE_MESSAGE
-            field.type_name.delete_prefix(".").split(".").join("::")
-          else
-            TYPE_MAPPING.fetch(field.type)
-          end
-        end
-
-        convert_type(
-          converted_type,
-          optional: field.label == :TYPE_OPTIONAL,
-          array: field.label == :LABEL_REPEATED && !map_field?(field),
-        )
-      end
-
-      def field_to_params(field)
-        [field.name, convert_field_type(field)]
-      end
-
-      def fields_to_params(fields)
-        fields
-          .flat_map { |field| field_to_params(field) }
-          .each_slice(2)
-          .to_h
-      end
-    end
-  end
-end
diff --git a/lib/protoboeuf/type_helper.rb b/lib/protoboeuf/type_helper.rb
new file mode 100644
index 0000000..a220665
--- /dev/null
+++ b/lib/protoboeuf/type_helper.rb
@@ -0,0 +1,104 @@
+# frozen_string_literal: true
+
+module ProtoBoeuf
+  module TypeHelper
+    TYPE_MAPPING = {
+      :TYPE_INT32 => "Integer",
+      :TYPE_SINT32 => "Integer",
+      :TYPE_UINT32 => "Integer",
+      :TYPE_INT64 => "Integer",
+      :TYPE_SINT64 => "Integer",
+      :TYPE_FIXED64 => "Integer",
+      :TYPE_SFIXED64 => "Integer",
+      :TYPE_FIXED32 => "Integer",
+      :TYPE_SFIXED32 => "Integer",
+      :TYPE_UINT64 => "Integer",
+      :TYPE_STRING => "String",
+      :TYPE_DOUBLE => "Float",
+      :TYPE_FLOAT => "Float",
+      :TYPE_BYTES => "String",
+      :TYPE_ENUM => "Symbol",
+      "google.protobuf.BoolValue" => "ProtoBoeuf::Protobuf::BoolValue",
+      "google.protobuf.Int32Value" => "ProtoBoeuf::Protobuf::Int32Value",
+      "google.protobuf.Int64Value" => "ProtoBoeuf::Protobuf::Int64Value",
+      "google.protobuf.UInt32Value" => "ProtoBoeuf::Protobuf::UInt32Value",
+      "google.protobuf.UInt64Value" => "ProtoBoeuf::Protobuf::UInt64Value",
+      "google.protobuf.FloatValue" => "ProtoBoeuf::Protobuf::FloatValue",
+      "google.protobuf.DoubleValue" => "ProtoBoeuf::Protobuf::DoubleValue",
+      "google.protobuf.StringValue" => "ProtoBoeuf::Protobuf::StringValue",
+      "google.protobuf.BytesValue" => "ProtoBoeuf::Protobuf::BytesValue",
+      "google.protobuf.Timestamp" => "ProtoBoeuf::Protobuf::Timestamp",
+    }.freeze
+
+    def type_signature(params: nil, returns: nil, newline: false)
+      return "" unless generate_types
+
+      sig = []
+      sig << "params(#{params.map { |k, v| "#{k}: #{convert_type(v)}" }.join(", ")})" if params
+      sig << "returns(#{returns})" if returns
+      sig << "void" unless returns
+
+      complete_sig = "sig { #{sig.join(".")} }"
+      complete_sig += "\n" if newline
+
+      complete_sig
+    end
+
+    def initialize_type_signature(fields)
+      return "" unless generate_types
+
+      type_signature(params: fields_to_params(fields), newline: true)
+    end
+
+    def reader_type_signature(field)
+      type_signature(returns: convert_field_type(field))
+    end
+
+    def extend_t_sig
+      return "" unless generate_types
+
+      "extend T::Sig"
+    end
+
+    private
+
+    def convert_type(converted_type, optional: false, array: false)
+      converted_type = "T::Array[#{converted_type}]" if array
+      converted_type = "T.nilable(#{converted_type})" if optional
+      converted_type
+    end
+
+    def convert_field_type(field)
+      converted_type = if map_field?(field)
+        map_type = self.map_type(field)
+        "T::Hash[#{convert_field_type(map_type.field[0])}, #{convert_field_type(map_type.field[1])}]"
+      else
+        case field.type
+        when :TYPE_BOOL
+          "T::Boolean"
+        when :TYPE_MESSAGE
+          field.type_name.delete_prefix(".").split(".").join("::")
+        else
+          TYPE_MAPPING.fetch(field.type)
+        end
+      end
+
+      convert_type(
+        converted_type,
+        optional: field.label == :TYPE_OPTIONAL,
+        array: field.label == :LABEL_REPEATED && !map_field?(field),
+      )
+    end
+
+    def field_to_params(field)
+      [field.name, convert_field_type(field)]
+    end
+
+    def fields_to_params(fields)
+      fields
+        .flat_map { |field| field_to_params(field) }
+        .each_slice(2)
+        .to_h
+    end
+  end
+end
diff --git a/test/gem_test.rb b/test/gem_test.rb
index b7c4ef9..8d135fa 100644
--- a/test/gem_test.rb
+++ b/test/gem_test.rb
@@ -4,29 +4,62 @@
 
 class GemTest < ProtoBoeuf::Test
   def test_can_be_required
-    Tempfile.create do |file|
-      file.write(<<~RUBY)
-        require "bundler/inline"
+    assert_rb_runs_successfully(<<~RUBY, "Failed to require the gem")
+      require "bundler/inline"
+
+      gemfile do
+        gem "protoboeuf", path: "#{__dir__}/..", require: true
+      end
+
+      def assert_autoload(mod, name)
+        # We need to escape the string interpolation so it doesn't evaluate before we actually write this code to disk.
+        raise "\#{mod}::\#{name} not configured to autoload" unless mod.autoload?(name)
+      end
+
+      assert_autoload(::ProtoBoeuf, :CodeGen)
+      assert_autoload(::ProtoBoeuf, :Google)
+      assert_autoload(::ProtoBoeuf::Google, :Api)
+      assert_autoload(::ProtoBoeuf::Google::Api, :FieldBehavior)
+      assert_autoload(::ProtoBoeuf::Google, :Protobuf)
+      assert_autoload(::ProtoBoeuf::Google::Protobuf, :Any)
+      assert_autoload(::ProtoBoeuf::Google::Protobuf, :FileDescriptorProto)
+      assert_autoload(::ProtoBoeuf::Google::Protobuf, :FileDescriptorSet)
+
+      exit 0
+    RUBY
+  end
+
+  def test_codegen_can_be_required
+    # Test that we fixed a circular require bug: https://github.com/Shopify/protoboeuf/issues/173
 
-        gemfile do
-          gem "protoboeuf", path: "#{__dir__}/..", require: true
-        end
+    _, stderr, _ = assert_rb_runs_successfully(<<~RUBY)
+      require "bundler/inline"
 
-        ::ProtoBoeuf
+      gemfile do
+        gem "protoboeuf", path: "#{__dir__}/..", require: false
+      end
 
-        # The following should autoloaded
-        ::ProtoBoeuf::CodeGen
-        ::ProtoBoeuf::Google::Api::FieldBehavior
-        ::ProtoBoeuf::Google::Protobuf::Any
-        ::ProtoBoeuf::Google::Protobuf::FileDescriptorProto
-        ::ProtoBoeuf::Google::Protobuf::FileDescriptorSet
+      require "protoboeuf"
+      require "protoboeuf/codegen"
 
-        exit 0
-      RUBY
+      exit 0
+    RUBY
 
+    refute_match(/warning: loading in progress, circular require considered harmful/, stderr)
+  end
+
+  private
+
+  def assert_rb_runs_successfully(ruby, msg = "Ruby returned non-zero exit status")
+    Tempfile.create do |file|
+      file.write(ruby)
       file.flush
 
-      assert(system(RbConfig.ruby, "-v", file.path), "Failed to require the gem")
+      stdout, stderr, status = Open3.capture3(RbConfig.ruby, "-v", file.path)
+
+      assert_equal(0, status, msg)
+
+      [stdout, stderr, status]
     end
   end
 end