diff --git a/velox/docs/develop/scalar-functions.rst b/velox/docs/develop/scalar-functions.rst
index 8a8af2badaa07..fa728a8627708 100644
--- a/velox/docs/develop/scalar-functions.rst
+++ b/velox/docs/develop/scalar-functions.rst
@@ -581,14 +581,16 @@ process. This set may not include all the rows. By default, a vector function
 is assumed to have the default null behavior, e.g. null in any input produces
 a null result. In this case, the expression evaluation engine will exclude
 rows with nulls from the “rows” specified in the call to “apply”. If a
-function has a different behavior for null inputs, it must override the
-isDefaultNullBehavior method to return false.
+function has a different behavior for null inputs, VectorFunctionMetadata's
+defaultNullBehavior must be set to false when it is registered.
 
 .. code-block:: c++
 
-    bool isDefaultNullBehavior() const override {
-      return false;
-    }
+    exec::registerStatefulVectorFunction(
+      prefix + "least",
+      leastSignatures(),
+      makeLeast,
+      exec::VectorFunctionMetadataBuilder().defaultNullBehavior(false).build());
 
 In this case, the “rows” parameter will include rows with null inputs and the
 function will need to handle these. By default, the function can assume that
diff --git a/velox/expression/VectorFunction.h b/velox/expression/VectorFunction.h
index abffc882d7ff0..1c1c467bae8e9 100644
--- a/velox/expression/VectorFunction.h
+++ b/velox/expression/VectorFunction.h
@@ -45,7 +45,7 @@ class VectorFunction {
   /// vector as flat or constant, but not dictionary encoded.
   ///
   /// Single-argument functions that specify null-in-null-out behavior, e.g.
-  /// isDefaultNullBehavior returns true, will never see a null row in 'rows'.
+  /// defaultNullBehavior is true, will never see a null row in 'rows'.
   /// Hence, they can safely assume that args[0] vector is flat or constant and
   /// has no nulls in specified positions.
   ///