diff --git a/grammar.js b/grammar.js
index aa2bbfad..1f6236bc 100644
--- a/grammar.js
+++ b/grammar.js
@@ -124,6 +124,7 @@ module.exports = grammar({
     keyword_start: _ => make_keyword("start"),
     keyword_restart: _ => make_keyword("restart"),
     keyword_key: _ => make_keyword("key"),
+    keyword_duplicate: _ => make_keyword("duplicate"),
     keyword_as: _ => make_keyword("as"),
     keyword_distinct: _ => make_keyword("distinct"),
     keyword_constraint: _ => make_keyword("constraint"),
@@ -2150,24 +2151,42 @@ module.exports = grammar({
         $._set_values,
       ),
       optional(
-        seq(
-          $.keyword_on,
-          $.keyword_conflict,
+        choice(
+          $._on_conflict,
+          $._on_duplicate_key_update,
+        ),
+      ),
+    ),
+
+    _on_conflict: $ => seq(
+      $.keyword_on,
+      $.keyword_conflict,
+      seq(
+        $.keyword_do,
+        choice(
+          $.keyword_nothing,
           seq(
-            $.keyword_do,
-            choice(
-              $.keyword_nothing,
-              seq(
-                $.keyword_update,
-                $._set_values,
-                optional($.where),
-              ),
-            ),
+            $.keyword_update,
+            $._set_values,
+            optional($.where),
           ),
         ),
       ),
     ),
 
+    _on_duplicate_key_update: $ => seq(
+      $.keyword_on,
+      $.keyword_duplicate,
+      $.keyword_key,
+      $.keyword_update,
+      $.assignment_list,
+    ),
+
+    assignment_list: $ => seq(
+      $.assignment,
+      repeat(seq(',', $.assignment)),
+    ),
+
     _insert_values: $ => seq(
       optional(alias($._column_list, $.list)),
       choice(
diff --git a/test/corpus/insert.txt b/test/corpus/insert.txt
index 7d225b2f..5ec111e8 100644
--- a/test/corpus/insert.txt
+++ b/test/corpus/insert.txt
@@ -140,7 +140,8 @@ RETURNING *;
     (returning
       (keyword_returning)
       (select_expression
-        (term value: (all_fields))))))
+        (term
+          value: (all_fields))))))
 
 ================================================================================
 Insert returning single column
@@ -449,7 +450,8 @@ FROM
             (select
               (keyword_select)
               (select_expression
-                (term (all_fields))))
+                (term
+                  (all_fields))))
             (from
               (keyword_from)
               (relation
@@ -513,7 +515,8 @@ FROM
             (select
               (keyword_select)
               (select_expression
-                (term (all_fields))))
+                (term
+                  (all_fields))))
             (from
               (keyword_from)
               (relation
@@ -561,3 +564,64 @@ INSERT INTO some_table
           (select_expression
             (term
               (literal))))))))
+
+================================================================================
+ON DUPLICATE KEY UPDATE
+================================================================================
+
+INSERT INTO table_1 (pk, col1, col2)
+VALUES
+  (1, 1, 1),
+  (2, 2, 2)
+ON DUPLICATE KEY UPDATE
+  pk = VALUES(pk),
+  col1 = 1,
+  col2 = "foo";
+
+--------------------------------------------------------------------------------
+
+(program
+  (statement
+    (insert
+      (keyword_insert)
+      (keyword_into)
+      (object_reference
+        name: (identifier))
+      (list
+        (column
+          (identifier))
+        (column
+          (identifier))
+        (column
+          (identifier)))
+      (keyword_values)
+      (list
+        (literal)
+        (literal)
+        (literal))
+      (list
+        (literal)
+        (literal)
+        (literal))
+      (keyword_on)
+      (keyword_duplicate)
+      (keyword_key)
+      (keyword_update)
+      (assignment_list
+        (assignment
+          left: (field
+            name: (identifier))
+          right: (invocation
+            (object_reference
+              name: (identifier))
+            parameter: (term
+              value: (field
+                name: (identifier)))))
+        (assignment
+          left: (field
+            name: (identifier))
+          right: (literal))
+        (assignment
+          left: (field
+            name: (identifier))
+          right: (literal))))))