#18628: clarify index entry for source file encoding declaration.
diff --git a/Doc/reference/lexical_analysis.rst b/Doc/reference/lexical_analysis.rst
index 2f31c85..52a09a8 100644
--- a/Doc/reference/lexical_analysis.rst
+++ b/Doc/reference/lexical_analysis.rst
@@ -104,9 +104,7 @@
 Encoding declarations
 ---------------------
 
-.. index::
-   single: source character set
-   single: encodings
+.. index:: source character set, encoding declarations (source file)
 
 If a comment in the first or second line of the Python script matches the
 regular expression ``coding[=:]\s*([-\w.]+)``, this comment is processed as an