diff --git a/datafusion/expr/src/udaf.rs b/datafusion/expr/src/udaf.rs
index 782e62618bf7..7aeeff3799fa 100644
--- a/datafusion/expr/src/udaf.rs
+++ b/datafusion/expr/src/udaf.rs
@@ -328,7 +328,7 @@ where
 ///             Field::new("ordering", DataType::UInt32, true)
 ///        ])
 ///    }
-///    fn documentation(&self) -> Documentation {
+///    fn documentation(&self) -> &Documentation {
 ///        &self.documentation  
 ///    }
 /// }
diff --git a/datafusion/expr/src/udf.rs b/datafusion/expr/src/udf.rs
index daa4b33cf3b3..b059b0419760 100644
--- a/datafusion/expr/src/udf.rs
+++ b/datafusion/expr/src/udf.rs
@@ -348,7 +348,7 @@ where
 ///    }
 ///    // The actual implementation would add one to the argument
 ///    fn invoke(&self, args: &[ColumnarValue]) -> Result<ColumnarValue> { unimplemented!() }
-///    fn documentation(&self) -> Documentation {
+///    fn documentation(&self) -> &Documentation {
 ///         &self.documentation
 ///     }
 /// }