gvars.patch

diff --git a/test/ruby/test_variable.rb b/test/ruby/test_variable.rb
index f04e358..6e69d56 100644
--- a/test/ruby/test_variable.rb
+++ b/test/ruby/test_variable.rb
@@ -103,6 +103,15 @@ class TestVariable < Test::Unit::TestCase
     assert_in_out_err(["-e", "$0='t'*1000;print $0"], "", /\At+\z/, [])
   end

+  def test_global_variables_captures
+    '' =~ //
+    refute global_variables.include?(:$1)
+    'a' =~ /(.)/
+    assert global_variables.include?(:$1)
+    'ab' =~ /(.)(.)/
+    assert global_variables.include?(:$2)
+  end
+
   def test_global_variable_poped
     assert_nothing_raised {
       EnvUtil.suppress_warning {
diff --git a/variable.c b/variable.c
index bb8b6db..00138cc 100644
--- a/variable.c
+++ b/variable.c
@@ -12,6 +12,7 @@
 **********************************************************************/

 #include "internal.h"
+#include "ruby/re.h"
 #include "ruby/st.h"
 #include "ruby/util.h"
 #include "constant.h"
@@ -901,14 +902,17 @@ VALUE
 rb_f_global_variables(void)
 {
     VALUE ary = rb_ary_new();
-    char buf[2];
-    int i;
+    VALUE backref = rb_backref_get();
+    char buf[7];
+    int i, len;

     st_foreach_safe(rb_global_tbl, gvar_i, ary);
+    if (RTEST(backref)) {
     buf[0] = '$';
-    for (i = 1; i <= 9; ++i) {
-	buf[1] = (char)(i + '0');
-	rb_ary_push(ary, ID2SYM(rb_intern2(buf, 2)));
+    for (i = 1; i < RMATCH_REGS(backref)->num_regs; ++i) {
+	len = snprintf(buf + 1, 6, "%d", i);
+	rb_ary_push(ary, ID2SYM(rb_intern2(buf, len + 1)));
+    }
     }
     return ary;
 }