diff --git a/include/ruby/ruby.h b/include/ruby/ruby.h
index 5a5bfe9621..7c7aa1798d 100644
--- a/include/ruby/ruby.h
+++ b/include/ruby/ruby.h
@@ -1905,6 +1905,9 @@ RUBY_EXTERN VALUE rb_mFConst;
 RUBY_EXTERN VALUE rb_mFileTest;
 RUBY_EXTERN VALUE rb_mGC;
 RUBY_EXTERN VALUE rb_mMath;
+RUBY_EXTERN VALUE rb_mProcGID;
+RUBY_EXTERN VALUE rb_mProcID_Syscall;
+RUBY_EXTERN VALUE rb_mProcUID;
 RUBY_EXTERN VALUE rb_mProcess;
 RUBY_EXTERN VALUE rb_mWaitReadable;
 RUBY_EXTERN VALUE rb_mWaitWritable;