1 files changed, 21 insertions, 5 deletions
diff --git a/lib/ffi/types.rb b/lib/ffi/types.rb
index 90f50c1..da214ee 100644
--- a/lib/ffi/types.rb
+++ b/lib/ffi/types.rb
@@ -37,8 +37,11 @@ module FFI
   # @param [Symbol] add new type definition's name to add
   # @return [Type]
   # Add a definition type to type definitions.
+  #
+  # The type definition is local per Ractor.
   def self.typedef(old, add)
-    TypeDefs[add] = self.find_type(old)
+    tm = custom_typedefs
+    tm[add] = self.find_type(old)
   end
 
   # (see FFI.typedef)
@@ -46,6 +49,14 @@ module FFI
     typedef old, add
   end
 
+  class << self
+    private def __typedef(old, add)
+      TypeDefs[add] = self.find_type(old)
+    end
+
+    private :custom_typedefs
+  end
+
 
   # @param [Type, DataConverter, Symbol] name
   # @param [Hash] type_map if nil, {FFI::TypeDefs} is used
@@ -57,9 +68,12 @@ module FFI
     if name.is_a?(Type)
       name
 
-    elsif type_map && type_map.has_key?(name)
+    elsif type_map&.has_key?(name)
       type_map[name]
 
+    elsif (tm=custom_typedefs).has_key?(name)
+      tm[name]
+
     elsif TypeDefs.has_key?(name)
       TypeDefs[name]
 
@@ -168,7 +182,7 @@ module FFI
     end
   end
 
-  typedef(StrPtrConverter, :strptr)
+  __typedef(StrPtrConverter, :strptr)
 
   # @param type +type+ is an instance of class accepted by {FFI.find_type}
   # @return [Numeric]
@@ -184,11 +198,13 @@ module FFI
       f.each_line { |line|
         if line.index(prefix) == 0
           new_type, orig_type = line.chomp.slice(prefix.length..-1).split(/\s*=\s*/)
-          typedef(orig_type.to_sym, new_type.to_sym)
+          __typedef(orig_type.to_sym, new_type.to_sym)
         end
       }
     end
-    typedef :pointer, :caddr_t
+    __typedef :pointer, :caddr_t
   rescue Errno::ENOENT
   end
+
+  FFI.make_shareable(TypeDefs)
 end