+diff -aur ruby-1.8.5.orig/array.c ruby-1.8.5/array.c
+--- ruby-1.8.5.orig/array.c 2006-06-24 16:53:36.000000000 +0200
++++ ruby-1.8.5/array.c 2006-11-12 11:58:46.187673233 +0100
+@@ -501,8 +501,16 @@
+ rb_ary_modify_check(ary);
+ if (RARRAY(ary)->len == 0) return Qnil;
+ top = RARRAY(ary)->ptr[0];
+- ary_make_shared(ary);
+- RARRAY(ary)->ptr++; /* shift ptr */
++ if (RARRAY(ary)->len < ARY_DEFAULT_SIZE && !FL_TEST(ary, ELTS_SHARED)) {
++ MEMMOVE(RARRAY(ary)->ptr, RARRAY(ary)->ptr + 1, VALUE, RARRAY(ary)->len - 1);
++ }
++ else {
++ if (!FL_TEST(ary, ELTS_SHARED)) {
++ RARRAY(ary)->ptr[0] = Qnil;
++ }
++ ary_make_shared(ary);
++ RARRAY(ary)->ptr++; /* shift ptr */
++ }
+ RARRAY(ary)->len--;
+
+ return top;