diff --git a/ext/extmk.rb b/ext/extmk.rb
index 939eb735659bee..81ab9ce8a51eb4 100755
--- a/ext/extmk.rb
+++ b/ext/extmk.rb
@@ -136,6 +136,14 @@ def extract_makefile(makefile, keep = true)
   true
 end
 
+def create_makefile(target, srcprefix = nil)
+  if $static and target.include?("/")
+    base = File.basename(target)
+    $defs << "-DInit_#{base}=Init_#{target.tr('/', '_')}"
+  end
+  super
+end
+
 def extmake(target, basedir = 'ext', maybestatic = true)
   FileUtils.mkpath target unless File.directory?(target)
   begin
@@ -546,7 +554,13 @@ def configuration(srcdir)
   end
 
   def create_makefile(*args, &block)
-    return super unless @gemname
+    unless @gemname
+      if $static and (target = args.first).include?("/")
+        base = File.basename(target)
+        $defs << "-DInit_#{base}=Init_#{target.tr('/', '_')}"
+      end
+      return super
+    end
     super(*args) do |conf|
       conf.find do |s|
         s.sub!(%r(^(srcdir *= *)\$\(top_srcdir\)/\.bundle/gems/[^/]+(?=/))) {
diff --git a/template/extinit.c.tmpl b/template/extinit.c.tmpl
index 7a9c910633bae3..e0b076b03c8c9b 100644
--- a/template/extinit.c.tmpl
+++ b/template/extinit.c.tmpl
@@ -1,5 +1,5 @@
 %# -*- C -*-
-% extinits = ARGV.map {|n| [n[%r[[^/.]+(?=\.[^/]*)?\z]], n]}
+% extinits = ARGV.map {|n| [n.tr('/', '_'), n]}
 #include "ruby/ruby.h"
 
 #define init(func, name) {	\
diff --git a/version.h b/version.h
index a0460419fd146c..9a904de7b3ea08 100644
--- a/version.h
+++ b/version.h
@@ -11,7 +11,7 @@
 # define RUBY_VERSION_MINOR RUBY_API_VERSION_MINOR
 #define RUBY_VERSION_TEENY 5
 #define RUBY_RELEASE_DATE RUBY_RELEASE_YEAR_STR"-"RUBY_RELEASE_MONTH_STR"-"RUBY_RELEASE_DAY_STR
-#define RUBY_PATCHLEVEL 258
+#define RUBY_PATCHLEVEL 259
 
 #define RUBY_RELEASE_YEAR 2024
 #define RUBY_RELEASE_MONTH 5