diff --git a/src/backend/xml/gnc-xml-helper.c b/src/backend/xml/gnc-xml-helper.c
index 1f22eabd9c..70a48cf289 100644
--- a/src/backend/xml/gnc-xml-helper.c
+++ b/src/backend/xml/gnc-xml-helper.c
@@ -1,7 +1,7 @@
 /********************************************************************\
  * gnc-xml-helper.h -- api for xml helpers                          *
  *                                                                  *
- * Copyright (C) 2001 James LewisMoss <dres@debian.org>             *
+ * Copyright (C) 2014 John Ralls <jralls@ceridwen.us>               *
  *                                                                  *
  * This program is free software; you can redistribute it and/or    *
  * modify it under the terms of the GNU General Public License as   *
@@ -25,26 +25,102 @@
 #include <glib.h>
 #include "gnc-xml-helper.h"
 
+
+/* The following applies to the utf8 array and decode function:
+ * Copyright (c) 2008-2009 Bjoern Hoehrmann <bjoern@hoehrmann.de>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+// Copyright (c) 2008-2009 Bjoern Hoehrmann <bjoern@hoehrmann.de>
+// See http://bjoern.hoehrmann.de/utf-8/decoder/dfa/ for details.
+
+#define UTF8_ACCEPT 0
+#define UTF8_REJECT 1
+
+static const uint8_t utf8d[] = {
+  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 00..1f
+  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 20..3f
+  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 40..5f
+  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 60..7f
+  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9, // 80..9f
+  7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, // a0..bf
+  8,8,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, // c0..df
+  0xa,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x4,0x3,0x3, // e0..ef
+  0xb,0x6,0x6,0x6,0x5,0x8,0x8,0x8,0x8,0x8,0x8,0x8,0x8,0x8,0x8,0x8, // f0..ff
+  0x0,0x1,0x2,0x3,0x5,0x8,0x7,0x1,0x1,0x1,0x4,0x6,0x1,0x1,0x1,0x1, // s0..s0 10f
+  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,1,1,1,1,1,0,1,0,1,1,1,1,1,1, // s1..s2 12f
+  1,2,1,1,1,1,1,2,1,2,1,1,1,1,1,1,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1, // s3..s4 14f
+  1,2,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1,1,1,1,1,1,3,1,3,1,1,1,1,1,1, // s5..s6 16f
+  1,3,1,1,1,1,1,3,1,3,1,1,1,1,1,1,1,3,1,1,1,1,1,1,1,1,1,1,1,1,1,1, // s7..s8 18f
+};
+
+static uint32_t inline
+decode(uint32_t* state, uint32_t* codep, uint32_t byte) {
+  uint32_t type = utf8d[byte];
+
+  *codep = (*state != UTF8_ACCEPT) ?
+    (byte & 0x3fu) | (*codep << 6) :
+    (0xff >> type) & (byte);
+
+  *state = utf8d[256 + *state*16 + type];
+  return *state;
+}
+
+
 xmlChar*
 checked_char_cast (gchar *val)
 {
-    const int length = -1; /* Assumes val is null-terminated */
-    gchar *end;
-    if (val == NULL) return NULL;
-    /* Replace any invalid UTF-8 characters with a sequence of '?' */
-    while (!g_utf8_validate (val, length, (const gchar**)(&end)))
-        *end = '?';
-    /* Replace any invalid (for XML) control characters (everything < 0x20
-     * except \n, \t, and \r) with '?'. Technically we should replace
-     * these with a numeric entity, but that will blow up the libxml
-     * functions that expect raw text. It seems unlikely that anyone
-     * would use intentionally use one of these characters anyway.
-     */
+    gchar *p = val;
+    uint32_t prev, curr;
+    uint8_t count;
+
+    for (prev = 0, curr = 0; *p; prev = curr, ++p)
+    {
+	uint32_t codep; /* We don't care, it's a throwaway */
+	if (*p && *p < 0x20 && *p != 0x09 &&
+	    *p != 0x0a && *p != 0x0d)
+	{
+	    *p = '?';
+	    continue;
+	}
+	if (*(uint8_t*)p < 0x80)
+	    continue;
+	switch (decode(&curr, &codep, *p))
+	{
+	    case UTF8_ACCEPT:
+		break;
+	    case UTF8_REJECT:
+		curr = UTF8_ACCEPT;
+		*p = '?';
+		if (prev != UTF8_ACCEPT)
+		    *(p - 1) = '?';
+		for (count = 0; count < prev / 3 + 1; ++count)
+		    *(++p) = '?';
+		break;
+	    default:
+		break;
+	}
+    }
 
-     for (end = val; *end; ++end)
-	if (*end > 0 && *end < 0x20 && *end != 0x09 &&
-	    *end != 0x0a && *end != 0x0d)
-	    *end = '?';
     return (xmlChar*)(val);
 }