diff --git a/grammar.js b/grammar.js
index 6f58f3ce..3d0953b8 100644
--- a/grammar.js
+++ b/grammar.js
@@ -235,6 +235,7 @@ module.exports = grammar({
     keyword_nowait: _ => make_keyword("nowait"),
     keyword_attribute: _ => make_keyword("attribute"),
     keyword_authorization: _ => make_keyword("authorization"),
+    keyword_action: _ => make_keyword("action"),
 
     keyword_trigger: _ => make_keyword('trigger'),
     keyword_function: _ => make_keyword("function"),
@@ -2274,13 +2275,31 @@ module.exports = grammar({
             seq(
               $.keyword_on,
               $.keyword_delete,
-              $.keyword_cascade,
+              $.referential_action,
+            ),
+          ),
+          optional(
+            seq(
+              $.keyword_on,
+              $.keyword_update,
+              $.referential_action,
             ),
           ),
         ),
       ),
     ),
 
+    referential_action: $ => choice(
+      seq($.keyword_no, $.keyword_action),
+      $.keyword_restrict,
+      $.keyword_cascade,
+      seq(
+        $.keyword_set,
+        choice($.keyword_null, $.keyword_default),
+        optional(paren_list($.identifier))
+      ),
+    ),
+
     ordered_columns: $ => paren_list(alias($.ordered_column, $.column), true),
 
     ordered_column: $ => seq(
diff --git a/test/corpus/alter.txt b/test/corpus/alter.txt
index d728ccf7..b8c9fc78 100644
--- a/test/corpus/alter.txt
+++ b/test/corpus/alter.txt
@@ -533,7 +533,6 @@ ALTER TABLE "Role" ADD CONSTRAINT "pkRole" PRIMARY KEY ("roleId");
             (column
               name: (literal))))))))
 
-
 ================================================================================
 Add foreign key constraint
 ================================================================================
@@ -568,7 +567,8 @@ FOREIGN KEY ("accountId") REFERENCES "Account" ("accountId") ON DELETE CASCADE;
               name: (literal)))
           (keyword_on)
           (keyword_delete)
-          (keyword_cascade))))))
+          (referential_action
+            (keyword_cascade)))))))
 
 ================================================================================
 MySQL: Rename table
@@ -1131,3 +1131,48 @@ OWNED BY numbers.number_sequences
       (object_reference
         (identifier)
         (identifier)))))
+
+================================================================================
+Add foreign key constraint
+================================================================================
+
+ALTER TABLE "AccountRole" ADD CONSTRAINT "fkAccountRoleAccount"
+FOREIGN KEY ("accountId") REFERENCES "Account" ("accountId")
+ON DELETE SET NULL
+ON UPDATE SET DEFAULT;
+
+--------------------------------------------------------------------------------
+
+(program
+  (statement
+    (alter_table
+      (keyword_alter)
+      (keyword_table)
+      (object_reference
+        (identifier))
+      (add_constraint
+        (keyword_add)
+        (keyword_constraint)
+        (identifier)
+        (constraint
+          (keyword_foreign)
+          (keyword_key)
+          (ordered_columns
+            (column
+              (literal)))
+          (keyword_references)
+          (object_reference
+            (identifier))
+          (ordered_columns
+            (column
+              (literal)))
+          (keyword_on)
+          (keyword_delete)
+          (referential_action
+            (keyword_set)
+            (keyword_null))
+          (keyword_on)
+          (keyword_update)
+          (referential_action
+            (keyword_set)
+            (keyword_default)))))))