diff --git a/moor/lib/src/runtime/query_builder/statements/insert.dart b/moor/lib/src/runtime/query_builder/statements/insert.dart
index 5ebf6d1b..cb4f3e97 100644
--- a/moor/lib/src/runtime/query_builder/statements/insert.dart
+++ b/moor/lib/src/runtime/query_builder/statements/insert.dart
@@ -92,7 +92,7 @@ class InsertStatement<T extends Table, D extends DataClass> {
   ///
   /// This method is used internally by moor. Consider using [insert] instead.
   GenerationContext createContext(Insertable<D> entry, InsertMode mode,
-      {DoUpdate onConflict}) {
+      {DoUpdate<T, D> onConflict}) {
     _validateIntegrity(entry);
 
     final rawValues = entry.toColumns(true);
@@ -146,7 +146,19 @@ class InsertStatement<T extends Table, D extends DataClass> {
     }
 
     if (onConflict != null) {
-      final updateSet = onConflict._createInsertable(table).toColumns(true);
+      final upsertInsertable = onConflict._createInsertable(table.asDslTable);
+
+      if (!identical(entry, upsertInsertable)) {
+        // We run a ON CONFLICT DO UPDATE, so make sure upsertInsertable is
+        // valid for updates.
+        // the identical check is a performance optimization - for the most
+        // common call (insertOnConflictUpdate) we don't have to check twice.
+        table
+            .validateIntegrity(upsertInsertable, isInserting: false)
+            .throwIfInvalid(upsertInsertable);
+      }
+
+      final updateSet = upsertInsertable.toColumns(true);
 
       ctx.buffer.write(' ON CONFLICT DO UPDATE SET ');
 
diff --git a/moor/test/insert_test.dart b/moor/test/insert_test.dart
index 4f190c1c..4b4f3bcf 100644
--- a/moor/test/insert_test.dart
+++ b/moor/test/insert_test.dart
@@ -68,21 +68,48 @@ void main() {
         {const TableUpdate('users', kind: UpdateKind.insert)}));
   });
 
-  test('enforces data integrity', () async {
-    InvalidDataException exception;
-    try {
-      await db.into(db.todosTable).insert(
-            const TodosTableCompanion(
-              // not declared as nullable in table definition
-              content: Value(null),
-            ),
-          );
-      fail('inserting invalid data did not throw');
-    } on InvalidDataException catch (e) {
-      exception = e;
-    }
+  group('enforces integrity', () {
+    test('for regular inserts', () async {
+      InvalidDataException exception;
+      try {
+        await db.into(db.todosTable).insert(
+              const TodosTableCompanion(
+                // not declared as nullable in table definition
+                content: Value(null),
+              ),
+            );
+        fail('inserting invalid data did not throw');
+      } on InvalidDataException catch (e) {
+        exception = e;
+      }
 
-    expect(exception.toString(), startsWith('InvalidDataException'));
+      expect(exception.toString(), startsWith('InvalidDataException'));
+    });
+
+    test("for upserts that aren't valid inserts", () {
+      expect(
+        () {
+          return db
+              .into(db.todosTable)
+              // content would be required
+              .insertOnConflictUpdate(const TodosTableCompanion());
+        },
+        throwsA(isA<InvalidDataException>()),
+      );
+    });
+
+    test("for upserts that aren't valid updates", () {
+      expect(
+        () {
+          final insert = TodosTableCompanion.insert(content: 'content');
+          const update = TodosTableCompanion(content: Value(null));
+          return db
+              .into(db.todosTable)
+              .insert(insert, onConflict: DoUpdate((_) => update));
+        },
+        throwsA(isA<InvalidDataException>()),
+      );
+    });
   });
 
   test("doesn't allow writing null rows", () {