diff -ruN ruby-1.8.4.orig/re.c ruby-1.8.4/re.c
--- ruby-1.8.4.orig/re.c	2005-12-13 12:27:51.000000000 +0900
+++ ruby-1.8.4/re.c	2006-07-19 18:07:59.000000000 +0900
@@ -70,10 +70,11 @@
 #endif
 
 int
-rb_memcicmp(p1, p2, len)
-    char *p1, *p2;
+rb_memcicmp(x, y, len)
+    const void *x, *y;
     long len;
 {
+    const unsigned char *p1 = x, *p2 = y;
     int tmp;
 
     while (len--) {
@@ -85,7 +86,7 @@
 
 int
 rb_memcmp(p1, p2, len)
-    char *p1, *p2;
+    const void *p1, *p2;
     long len;
 {
     if (!ruby_ignorecase) {
@@ -96,11 +97,11 @@
 
 long
 rb_memsearch(x0, m, y0, n)
-    char *x0, *y0;
+    const void *x0, *y0;
     long m, n;
 {
-    unsigned char *x = (unsigned char *)x0, *y = (unsigned char *)y0;
-    unsigned char *s, *e;
+    const unsigned char *x = (unsigned char *)x0, *y = (unsigned char *)y0;
+    const unsigned char *s, *e;
     long i;
     int d;
     unsigned long hx, hy;
@@ -1332,6 +1333,8 @@
 {
     struct RRegexp *re = RREGEXP(obj);
 
+    if (!OBJ_TAINTED(obj) && rb_safe_level() >= 4)
+       rb_raise(rb_eSecurityError, "Insecure: can't modify regexp");
     if (re->ptr) re_free_pattern(re->ptr);
     if (re->str) free(re->str);
     re->ptr = 0;
diff -ruN ruby-1.8.4.orig/intern.h ruby-1.8.4/intern.h
--- ruby-1.8.4.orig/intern.h	2006-07-19 18:13:49.000000000 +0900
+++ ruby-1.8.4/intern.h	2006-07-19 18:20:34.000000000 +0900
@@ -353,9 +353,9 @@
 VALUE rb_range_beg_len _((VALUE, long*, long*, long, int));
 VALUE rb_length_by_each _((VALUE));
 /* re.c */
-int rb_memcmp _((char*,char*,long));
-int rb_memcicmp _((char*,char*,long));
-long rb_memsearch _((char*,long,char*,long));
+int rb_memcmp _((const void*,const void*,long));
+int rb_memcicmp _((const void*,const void*,long));
+long rb_memsearch _((const void*,long,const void*,long));
 VALUE rb_reg_nth_defined _((int, VALUE));
 VALUE rb_reg_nth_match _((int, VALUE));
 VALUE rb_reg_last_match _((VALUE));