diff --git a/ext/coverage/coverage.c b/ext/coverage/coverage.c
index 41f33f4fb8c9f3..1b0280b460ab81 100644
--- a/ext/coverage/coverage.c
+++ b/ext/coverage/coverage.c
@@ -164,14 +164,14 @@ rb_coverage_resume(VALUE klass)
 
 /*
  * call-seq:
- *    Coverage.start                                                          => nil
- *    Coverage.start(:all)                                                    => nil
- *    Coverage.start(lines: bool, branches: bool, methods: bool, eval: bool)  => nil
- *    Coverage.start(oneshot_lines: true)                                     => nil
- *
- * Enables the coverage measurement.
- * See the documentation of Coverage class in detail.
- * This is equivalent to Coverage.setup and Coverage.resume.
+ *    Coverage.start -> nil
+ *    Coverage.start(type) -> nil
+ *    Coverage.start(lines: false, branches: false, methods: false, eval: false, oneshot_lines: false) -> nil
+ *
+ * Enables coverage measurement.
+ * This method is equivalent to calling Coverage.setup with the arguments provided,
+ * and then calling Coverage.resume. See their respective documentation for more
+ * details.
  */
 static VALUE
 rb_coverage_start(int argc, VALUE *argv, VALUE klass)
diff --git a/ext/win32/lib/win32/registry.rb b/ext/win32/lib/win32/registry.rb
index 734d6987a2518a..5f8099baa2c160 100644
--- a/ext/win32/lib/win32/registry.rb
+++ b/ext/win32/lib/win32/registry.rb
@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 require 'fiddle/import'
 
+# Generic namespace for Windows platform-specific features.
 module Win32
   # :stopdoc:
   WCHAR = Encoding::UTF_16LE
diff --git a/ext/win32/lib/win32/resolv.rb b/ext/win32/lib/win32/resolv.rb
index 8d631a21403f4c..01e1bda351f990 100644
--- a/ext/win32/lib/win32/resolv.rb
+++ b/ext/win32/lib/win32/resolv.rb
@@ -7,7 +7,7 @@
 require 'win32/resolv.so'
 
 module Win32
-  module Resolv
+  module Resolv # :nodoc:
     # Error at Win32 API
     class Error < StandardError
       # +code+ Win32 Error code
diff --git a/ext/win32/resolv/resolv.c b/ext/win32/resolv/resolv.c
index b2d377df9fffc6..9150df5dc11a27 100644
--- a/ext/win32/resolv/resolv.c
+++ b/ext/win32/resolv/resolv.c
@@ -53,6 +53,7 @@ wchar_to_utf8(const WCHAR *w, int n)
     return str;
 }
 
+/* :nodoc: */
 static VALUE
 get_dns_server_list(VALUE self)
 {
@@ -81,7 +82,6 @@ get_dns_server_list(VALUE self)
     return nameservers;
 }
 
-
 static const WCHAR TCPIP_Params[] = L"SYSTEM\\CurrentControlSet\\Services\\Tcpip\\Parameters";
 
 static void
@@ -116,6 +116,7 @@ reg_open_key(VALUE klass, HKEY hkey, const WCHAR *wname)
     return rb_ensure(rb_yield, k, hkey_close, k);
 }
 
+/* :nodoc: */
 static VALUE
 tcpip_params_open(VALUE klass)
 {
diff --git a/lib/timeout.rb b/lib/timeout.rb
index e293e3be7c9eea..eb66e586df20e3 100644
--- a/lib/timeout.rb
+++ b/lib/timeout.rb
@@ -305,6 +305,7 @@ def self.timeout(sec, klass = nil, message = nil, &block)   #:yield: +sec+
     end
   end
 
+  # See Timeout.timeout
   private def timeout(*args, &block)
     Timeout.timeout(*args, &block)
   end
diff --git a/ractor_sync.c b/ractor_sync.c
index a346ea497bc4a4..809469eeccd763 100644
--- a/ractor_sync.c
+++ b/ractor_sync.c
@@ -28,27 +28,15 @@ ractor_port_mark(void *ptr)
     }
 }
 
-static void
-ractor_port_free(void *ptr)
-{
-    SIZED_FREE((struct ractor_port *)ptr);
-}
-
-static size_t
-ractor_port_memsize(const void *ptr)
-{
-    return sizeof(struct ractor_port);
-}
-
 static const rb_data_type_t ractor_port_data_type = {
     "ractor/port",
     {
         ractor_port_mark,
-        ractor_port_free,
-        ractor_port_memsize,
+        RUBY_TYPED_DEFAULT_FREE,
+        NULL, // memsize
         NULL, // update
     },
-    0, 0, RUBY_TYPED_FREE_IMMEDIATELY | RUBY_TYPED_WB_PROTECTED | RUBY_TYPED_FROZEN_SHAREABLE,
+    0, 0, RUBY_TYPED_FREE_IMMEDIATELY | RUBY_TYPED_WB_PROTECTED | RUBY_TYPED_FROZEN_SHAREABLE | RUBY_TYPED_EMBEDDABLE,
 };
 
 static st_data_t
@@ -62,8 +50,7 @@ static struct ractor_port *
 RACTOR_PORT_PTR(VALUE self)
 {
     VM_ASSERT(rb_typeddata_is_kind_of(self, &ractor_port_data_type));
-    struct ractor_port *rp = DATA_PTR(self);
-    return rp;
+    return RTYPEDDATA_GET_DATA(self);
 }
 
 static VALUE