diff --git a/src/calibre/utils/icu.py b/src/calibre/utils/icu.py
index 41f9abd0c2..584ae8ad45 100644
--- a/src/calibre/utils/icu.py
+++ b/src/calibre/utils/icu.py
@@ -282,10 +282,7 @@ def partition_by_first_letter(items, reverse=False, key=lambda x:x):
 string_length = _icu.string_length if is_narrow_build else len
 
 # Return the number of UTF-16 codepoints in a string
-try:
-    utf16_length = len if is_narrow_build else _icu.utf16_length
-except AttributeError:
-    utf16_length = len  # People running from source
+utf16_length = len if is_narrow_build else _icu.utf16_length
 
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