diff --git a/packages/flow-runtime-cli/src/__tests__/__fixtures__/js-flow-definitions/index.js.flow b/packages/flow-runtime-cli/src/__tests__/__fixtures__/js-flow-definitions/index.js.flow
new file mode 100644
index 00000000..a8f15a27
--- /dev/null
+++ b/packages/flow-runtime-cli/src/__tests__/__fixtures__/js-flow-definitions/index.js.flow
@@ -0,0 +1,5 @@
+declare module 'fixture-package' {
+  declare class ExternalUser {
+    name: string;
+  }
+}
diff --git a/packages/flow-runtime-cli/src/__tests__/crawlTypeDefinitions.test.js b/packages/flow-runtime-cli/src/__tests__/crawlTypeDefinitions.test.js
new file mode 100644
index 00000000..2dc83c9f
--- /dev/null
+++ b/packages/flow-runtime-cli/src/__tests__/crawlTypeDefinitions.test.js
@@ -0,0 +1,15 @@
+/* @flow */
+
+import {ok} from 'assert';
+import path from 'path';
+import crawlTypeDefinitions from '../crawlTypeDefinitions';
+
+describe('Crawl Type Definitions', () => {
+  it('discovers definitions from .js.flow files', async () => {
+    const graph = await crawlTypeDefinitions([
+      path.resolve(__dirname, '__fixtures__/js-flow-definitions')
+    ]);
+
+    ok(graph.get('fixture-package', 'ExternalUser'));
+  });
+});
diff --git a/packages/flow-runtime-cli/src/findFiles.js b/packages/flow-runtime-cli/src/findFiles.js
index d5dc233b..d3cf1fc0 100644
--- a/packages/flow-runtime-cli/src/findFiles.js
+++ b/packages/flow-runtime-cli/src/findFiles.js
@@ -22,8 +22,12 @@ async function collectFiles (fileOrDir: string, collected: string[]): Promise<st
       await collectFiles(path.join(fileOrDir, item), collected);
     }
   }
-  else if (collected.indexOf(fileOrDir) === -1 && /\.js(x|m)?$/.test(fileOrDir)) {
+  else if (collected.indexOf(fileOrDir) === -1 && isJavaScriptFile(fileOrDir)) {
     collected.push(fileOrDir);
   }
   return collected;
 }
+
+function isJavaScriptFile (filename: string): boolean {
+  return /\.js(x|m)?$/.test(filename) || /\.js\.flow$/.test(filename);
+}