diff --git a/libguile/ChangeLog b/libguile/ChangeLog
index f56590fbf..76d921d07 100644
--- a/libguile/ChangeLog
+++ b/libguile/ChangeLog
@@ -1,3 +1,22 @@
+2006-11-17  Neil Jerram  <neil@ossau.uklinux.net>
+
+	Integration of patch from Daniel Ridge to allow strings in 1.6.x
+	to have length up to 2^32 - 1, instead of 2^24 - 1 as currently.
+	All changes are subject to #ifdef GUILE_EXPERIMENTAL_BIG_STRINGS;
+	GUILE_EXPERIMENTAL_BIG_STRINGS is _not_ defined by default, and we
+	have no intention of changing this within the official 1.6.x
+	series.  The only reason for integrating this is as a convenience
+	for the contributor, as and when we make further 1.6.x releases.
+	
+	* strings.h: If GUILE_EXPERIMENTAL_BIG_STRINGS is defined, use
+	different definitions for SCM_STRING_MAX_LENGTH, SCM_STRING_LENGTH
+	and SCM_SET_STRING_LENGTH, and add new convenience macro
+	SCM_SET_SUBSTRING_LENGTH.
+
+	* strings.c (scm_makstr, scm_take_str, scm_allocate_string,
+	scm_make_shared_substring): Allocate a double cell for a string,
+	if GUILE_EXPERIMENTAL_BIG_STRINGS is defined.
+
 2006-10-03  Kevin Ryde  <user42@zip.com.au>
 
 	* eval.c (SCM_APPLY): For scm_tc7_subr_2o, throw wrong-num-args on 0
diff --git a/libguile/strings.c b/libguile/strings.c
index 85be65f8d..209f4f8b1 100644
--- a/libguile/strings.c
+++ b/libguile/strings.c
@@ -131,7 +131,11 @@ scm_makstr (size_t len, int dummy)
   mem = (char *) scm_must_malloc (len + 1, FUNC_NAME);
   mem[len] = 0;
 
+#ifndef GUILE_EXPERIMENTAL_BIG_STRINGS
   SCM_NEWCELL (s);
+#else
+  SCM_NEWCELL2 (s);
+#endif
   SCM_SET_STRING_CHARS (s, mem);
   SCM_SET_STRING_LENGTH (s, len);
 
@@ -173,7 +177,11 @@ scm_take_str (char *s, size_t len)
 
   SCM_ASSERT_RANGE (2, scm_ulong2num (len), len <= SCM_STRING_MAX_LENGTH);
 
+#ifndef GUILE_EXPERIMENTAL_BIG_STRINGS
   SCM_NEWCELL (answer);
+#else
+  SCM_NEWCELL2 (answer);
+#endif
   SCM_SET_STRING_CHARS (answer, s);
   SCM_SET_STRING_LENGTH (answer, len);
   scm_done_malloc (len + 1);
@@ -241,7 +249,11 @@ scm_allocate_string (size_t len)
   mem = (char *) scm_must_malloc (len + 1, FUNC_NAME);
   mem[len] = 0;
 
+#ifndef GUILE_EXPERIMENTAL_BIG_STRINGS
   SCM_NEWCELL (s);
+#else
+  SCM_NEWCELL2 (s);
+#endif
   SCM_SET_STRING_CHARS (s, mem);
   SCM_SET_STRING_LENGTH (s, len);
 
@@ -415,13 +427,26 @@ SCM_DEFINE (scm_make_shared_substring, "make-shared-substring", 1, 2, 0,
 
   SCM_VALIDATE_ROSTRING (1,str);
   SCM_VALIDATE_INUM_DEF_COPY (2,start,0,f);
+#ifndef GUILE_EXPERIMENTAL_BIG_STRINGS
   SCM_VALIDATE_INUM_DEF_COPY (3,end,SCM_ROLENGTH(str),t);
+#else
+  SCM_VALIDATE_INUM_DEF_COPY (3,end,SCM_STRING_LENGTH(str),t);
+#endif
 
   SCM_ASSERT_RANGE (2,start,(f >= 0));
+#ifndef GUILE_EXPERIMENTAL_BIG_STRINGS
   SCM_ASSERT_RANGE (3,end, (f <= t) && (t <= SCM_ROLENGTH (str)));
+#else
+  SCM_ASSERT_RANGE (3,end, (f <= t) && (t <= SCM_STRING_LENGTH (str)));
+#endif
 
+#ifndef GUILE_EXPERIMENTAL_BIG_STRINGS
   SCM_NEWCELL (answer);
   SCM_NEWCELL (len_str);
+#else
+  SCM_NEWCELL2 (answer);
+  SCM_NEWCELL2 (len_str);
+#endif
 
   SCM_DEFER_INTS;
   if (SCM_SUBSTRP (str))
@@ -433,14 +458,22 @@ SCM_DEFINE (scm_make_shared_substring, "make-shared-substring", 1, 2, 0,
       SCM_SETCAR (len_str, SCM_MAKINUM (f));
       SCM_SETCDR (len_str, SCM_SUBSTR_STR (str));
       SCM_SETCDR (answer, len_str);
+#ifndef GUILE_EXPERIMENTAL_BIG_STRINGS
       SCM_SETLENGTH (answer, t - f, scm_tc7_substring);
+#else
+      SCM_SET_SUBSTRING_LENGTH (answer, t - f);
+#endif
     }
   else
     {
       SCM_SETCAR (len_str, SCM_MAKINUM (f));
       SCM_SETCDR (len_str, str);
       SCM_SETCDR (answer, len_str);
+#ifndef GUILE_EXPERIMENTAL_BIG_STRINGS
       SCM_SETLENGTH (answer, t - f, scm_tc7_substring);
+#else
+      SCM_SET_SUBSTRING_LENGTH (answer, t - f);
+#endif
     }
   SCM_ALLOW_INTS;
   return answer;
diff --git a/libguile/strings.h b/libguile/strings.h
index 512303882..a79ec60bf 100644
--- a/libguile/strings.h
+++ b/libguile/strings.h
@@ -55,10 +55,22 @@
 #define SCM_STRING_CHARS(x) ((char *) (SCM_CELL_WORD_1 (x)))
 #endif
 #define SCM_SET_STRING_CHARS(s, c) (SCM_SET_CELL_WORD_1 ((s), (c)))
+
+#ifndef GUILE_EXPERIMENTAL_BIG_STRINGS
+
 #define SCM_STRING_MAX_LENGTH ((1UL << 24) - 1UL)
 #define SCM_STRING_LENGTH(x) ((size_t) (SCM_CELL_WORD_0 (x) >> 8))
 #define SCM_SET_STRING_LENGTH(s, l) (SCM_SET_CELL_WORD_0 ((s), (((long) (l)) << 8) + scm_tc7_string))
 
+#else
+
+#define SCM_STRING_MAX_LENGTH ((1UL << (SCM_C_BVEC_LIMB_BITS)) - 1UL)
+#define SCM_STRING_LENGTH(x) ((size_t) (SCM_CELL_WORD_2 (x)))
+#define SCM_SET_STRING_LENGTH(s, l) (SCM_SET_CELL_WORD_0 ((s), scm_tc7_string), SCM_SET_CELL_WORD_2 ((s), (((long) (l)))))
+#define SCM_SET_SUBSTRING_LENGTH(s, l) (SCM_SET_CELL_WORD_0 ((s), scm_tc7_substring), SCM_SET_CELL_WORD_2 ((s), (((long) (l)))))
+
+#endif
+
 #define SCM_STRING_COERCE_0TERMINATION_X(x) \
   { if (!SCM_IMP (x) && (SCM_TYP7 (x) == scm_tc7_substring)) \
       x = scm_mem2string (SCM_STRING_CHARS (x), SCM_STRING_LENGTH (x)); }