diff --git a/pkgs/development/libraries/glibc/default.nix b/pkgs/development/libraries/glibc/default.nix
index 0b096bfd66e..7aea33cc891 100644
--- a/pkgs/development/libraries/glibc/default.nix
+++ b/pkgs/development/libraries/glibc/default.nix
@@ -32,6 +32,9 @@ stdenv.mkDerivation {
     # This is a patch to make glibc compile under GCC 3.3.  Presumably
     # later releases of glibc won't need this.
 #    ./glibc-2.3.2-sscanf-1.patch
+
+    # Fix for localedata loading bug.
+    ./loadlocale.patch
   ];
 
   inherit kernelHeaders installLocales;
diff --git a/pkgs/development/libraries/glibc/loadlocale.patch b/pkgs/development/libraries/glibc/loadlocale.patch
new file mode 100644
index 00000000000..5bd00805200
--- /dev/null
+++ b/pkgs/development/libraries/glibc/loadlocale.patch
@@ -0,0 +1,67 @@
+This patch fixes
+http://sources.redhat.com/bugzilla/show_bug.cgi?id=356, "localedata:
+tests-mbwc/tst_iswalnum segfaults during make check".
+
+===================================================================
+RCS file: /cvs/glibc/libc/locale/loadlocale.c,v
+retrieving revision 1.44
+retrieving revision 1.45
+diff -u -r1.44 -r1.45
+--- libc/locale/loadlocale.c	2003/09/03 07:54:22	1.44
++++ libc/locale/loadlocale.c	2004/09/26 05:48:14	1.45
+@@ -1,5 +1,5 @@
+ /* Functions to read locale data files.
+-   Copyright (C) 1996-2001, 2002, 2003 Free Software Foundation, Inc.
++   Copyright (C) 1996-2001, 2002, 2003, 2004 Free Software Foundation, Inc.
+    This file is part of the GNU C Library.
+    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
+ 
+@@ -115,15 +115,45 @@
+ 	  __set_errno (EINVAL);
+ 	  return NULL;
+ 	}
+-      if (__builtin_expect (_nl_value_types[category][cnt] == word, 0))
++
++      /* Determine the type.  There is one special case: the LC_CTYPE
++	 category can have more elements than there are in the
++	 _nl_value_type_LC_XYZ array.  There are all pointers.  */
++      switch (category)
++	{
++#define CATTEST(cat) \
++	case LC_##cat:							      \
++	  assert (cnt < (sizeof (_nl_value_type_LC_##cat)		      \
++			 / sizeof (_nl_value_type_LC_##cat[0])));	      \
++	  break
++	  CATTEST (NUMERIC);
++	  CATTEST (TIME);
++	  CATTEST (COLLATE);
++	  CATTEST (MONETARY);
++	  CATTEST (MESSAGES);
++	  CATTEST (PAPER);
++	  CATTEST (NAME);
++	  CATTEST (ADDRESS);
++	  CATTEST (TELEPHONE);
++	  CATTEST (MEASUREMENT);
++	  CATTEST (IDENTIFICATION);
++	default:
++	  assert (category == LC_CTYPE);
++	  break;
++	}
++
++      if ((category == LC_CTYPE
++	   && cnt >= (sizeof (_nl_value_type_LC_CTYPE)
++		      / sizeof (_nl_value_type_LC_CTYPE[0])))
++	  || __builtin_expect (_nl_value_types[category][cnt] != word, 1))
++	newdata->values[cnt].string = newdata->filedata + idx;
++      else
+ 	{
+ 	  if (idx % __alignof__ (u_int32_t) != 0)
+ 	    goto puntdata;
+ 	  newdata->values[cnt].word =
+ 	    *((const u_int32_t *) (newdata->filedata + idx));
+ 	}
+-      else
+-	newdata->values[cnt].string = newdata->filedata + idx;
+     }
+ 
+   return newdata;