diff --git a/integrationTests/flow/.flowconfig b/integrationTests/flow/.flowconfig
new file mode 100644
index 0000000000..872c3947a6
--- /dev/null
+++ b/integrationTests/flow/.flowconfig
@@ -0,0 +1,8 @@
+[include]
+./index.mjs
+
+[declarations]
+.*/node_modules/.*
+
+[options]
+include_warnings=true
diff --git a/integrationTests/flow/index.mjs b/integrationTests/flow/index.mjs
new file mode 100644
index 0000000000..ee14390b35
--- /dev/null
+++ b/integrationTests/flow/index.mjs
@@ -0,0 +1,54 @@
+// @flow strict
+
+import { parse } from 'graphql/language';
+import { GraphQLString, GraphQLSchema, GraphQLObjectType } from 'graphql/type';
+import { type ExecutionResult, execute } from 'graphql/execution';
+import { graphqlSync } from 'graphql';
+
+interface SomeExtension {
+  number: number;
+  string: string;
+}
+
+const example: SomeExtension = {
+  number: 42,
+  string: 'Meaning of life',
+};
+
+const queryType: GraphQLObjectType = new GraphQLObjectType({
+  name: 'Query',
+  fields: {
+    sayHi: {
+      type: GraphQLString,
+      args: {
+        who: {
+          type: GraphQLString,
+          extensions: {
+            someArgumentExtension: example,
+          },
+        },
+      },
+      resolve: (_root, args) => 'Hello ' + (args.who || 'World'),
+      extensions: {
+        someFieldExtension: example,
+      },
+    },
+  },
+  extensions: {
+    someObjectExtension: example,
+  },
+});
+
+const schema: GraphQLSchema = new GraphQLSchema({
+  query: queryType,
+});
+
+const result: ExecutionResult = graphqlSync({
+  schema,
+  source: `
+    query helloWho($who: String){
+      test(who: $who)
+    }
+  `,
+  variableValues: { who: 'Dolly' },
+});
diff --git a/integrationTests/flow/package.json b/integrationTests/flow/package.json
new file mode 100644
index 0000000000..8a87590458
--- /dev/null
+++ b/integrationTests/flow/package.json
@@ -0,0 +1,10 @@
+{
+  "private": true,
+  "scripts": {
+    "test": "flow check"
+  },
+  "dependencies": {
+    "graphql": "file:../graphql.tgz",
+    "flow-bin": "0.135.0"
+  }
+}
diff --git a/integrationTests/integration-test.js b/integrationTests/integration-test.js
index c0371f676e..9ccaddd736 100644
--- a/integrationTests/integration-test.js
+++ b/integrationTests/integration-test.js
@@ -39,6 +39,10 @@ describe('Integration Tests', () => {
     testOnNodeProject('ts');
   }).timeout(40000);
 
+  it('Should compile with Flow', () => {
+    testOnNodeProject('flow');
+  }).timeout(10000);
+
   it('Should work on all supported node versions', () => {
     testOnNodeProject('node');
   }).timeout(40000);
diff --git a/resources/build-npm.js b/resources/build-npm.js
index fbc26c73e2..38793cac67 100644
--- a/resources/build-npm.js
+++ b/resources/build-npm.js
@@ -19,7 +19,8 @@ if (require.main === module) {
 
     fs.mkdirSync(path.dirname(destPath), { recursive: true });
     if (filepath.endsWith('.js')) {
-      fs.copyFileSync(srcPath, destPath + '.flow');
+      const flowBody = '// @flow strict\n' + fs.readFileSync(srcPath, 'utf-8');
+      fs.writeFileSync(destPath + '.flow', flowBody);
 
       const cjs = babelBuild(srcPath, { envName: 'cjs' });
       fs.writeFileSync(destPath, cjs);