diff --git a/src/calibre/utils/icu.c b/src/calibre/utils/icu.c
index 2ff1f33d6d..16b280b854 100644
--- a/src/calibre/utils/icu.c
+++ b/src/calibre/utils/icu.c
@@ -649,12 +649,26 @@ end:
 } // }}}
 
 // BreakIterator.split2 {{{
+
+static inline void
+unicode_code_point_count(UChar **count_start, int32_t *last_count, int *last_count32, int32_t *word_start, int32_t *sz) {
+	int32_t chars_to_new_word_from_last_pos = *word_start - *last_count;
+	int32_t sz32 = u_countChar32(*count_start + chars_to_new_word_from_last_pos, *sz);
+	int32_t codepoints_to_new_word_from_last_pos = u_countChar32(*count_start, chars_to_new_word_from_last_pos);
+	*count_start += chars_to_new_word_from_last_pos + *sz;
+	*last_count += chars_to_new_word_from_last_pos + *sz;
+	*last_count32 += codepoints_to_new_word_from_last_pos;
+	*word_start = *last_count32;
+	*last_count32 += sz32;
+	*sz = sz32;
+}
+
 static PyObject *
 icu_BreakIterator_split2(icu_BreakIterator *self, PyObject *args) {
 
-    int32_t word_start = 0, p = 0, sz = 0, last_pos = 0, last_sz = 0;
+    int32_t word_start = 0, p = 0, sz = 0, last_pos = 0, last_sz = 0, last_count = 0, last_count32 = 0;
     int is_hyphen_sep = 0, leading_hyphen = 0, trailing_hyphen = 0;
-    UChar sep = 0;
+    UChar sep = 0, *count_start = self->text;
     PyObject *ans = NULL, *temp = NULL, *t = NULL;
 
     ans = PyList_New(0);
@@ -681,9 +695,8 @@ icu_BreakIterator_split2(icu_BreakIterator *self, PyObject *args) {
                 if (IS_HYPHEN_CHAR(sep)) trailing_hyphen = 1;
             }
             last_pos = p;
-#ifdef Py_UNICODE_WIDE
-            sz = u_countChar32(self->text + word_start, sz);
-            word_start = u_countChar32(self->text, word_start);
+#if defined(Py_UNICODE_WIDE) || PY_MAJOR_VERSION > 2
+			unicode_code_point_count(&count_start, &last_count, &last_count32, &word_start, &sz);
 #endif
             if (is_hyphen_sep && PyList_GET_SIZE(ans) > 0) {
                 sz = last_sz + sz + trailing_hyphen;
diff --git a/src/calibre/utils/icu_test.py b/src/calibre/utils/icu_test.py
index 50fe699bb0..ec9169c5f3 100644
--- a/src/calibre/utils/icu_test.py
+++ b/src/calibre/utils/icu_test.py
@@ -162,7 +162,7 @@ class TestICU(unittest.TestCase):
 
     def test_break_iterator(self):
         ' Test the break iterator '
-        from calibre.spell.break_iterator import split_into_words as split, index_of, split_into_words_and_positions
+        from calibre.spell.break_iterator import split_into_words as split, index_of, split_into_words_and_positions, count_words
         for q in ('one two three', ' one two three', 'one\ntwo  three ', ):
             self.ae(split(unicode_type(q)), ['one', 'two', 'three'], 'Failed to split: %r' % q)
         self.ae(split(u'I I\'m'), ['I', "I'm"])
@@ -171,6 +171,7 @@ class TestICU(unittest.TestCase):
         self.ae(split(u'-one a-b-c-d e'), ['-one', 'a-b-c-d', 'e'])
         self.ae(split(u'-one -a-b-c-d- e'), ['-one', '-a-b-c-d-', 'e'])
         self.ae(split_into_words_and_positions('one \U0001f431 three'), [(0, 3), (7 if icu.is_narrow_build else 6, 5)])
+        self.ae(count_words('a b c d e f'), 6)
         for needle, haystack, pos in (
                 ('word', 'a word b', 2),
                 ('word', 'a word', 2),