diff --git a/docs/src/main/sphinx/functions/aggregate.rst b/docs/src/main/sphinx/functions/aggregate.rst
index 4a8c8fe8f4c0..7f0042cff86f 100644
--- a/docs/src/main/sphinx/functions/aggregate.rst
+++ b/docs/src/main/sphinx/functions/aggregate.rst
@@ -144,7 +144,7 @@ General aggregate functions
 
     Returns the geometric mean of all input values.
 
-.. function:: listagg(x, separator)
+.. function:: listagg(x, separator) -> varchar
 
     Returns the concatenated input values, separated by the ``separator`` string.