diff --git a/src/tiny-invariant.flow.js b/src/tiny-invariant.flow.js
deleted file mode 100644
index 0f534cc..0000000
--- a/src/tiny-invariant.flow.js
+++ /dev/null
@@ -1,12 +0,0 @@
-// @flow
-// This file is not actually executed
-// It is just used by flow for typing
-
-const prefix: string = 'Invariant failed';
-
-export default function invariant(condition: mixed, message?: string | (() => string)) {
-  if (condition) {
-    return;
-  }
-  throw new Error(`${prefix}: ${message || ''}`);
-}
diff --git a/src/tiny-invariant.js.flow b/src/tiny-invariant.js.flow
new file mode 100644
index 0000000..fc577df
--- /dev/null
+++ b/src/tiny-invariant.js.flow
@@ -0,0 +1,8 @@
+// @flow
+
+declare module "tiny-invariant" {
+  declare export default function invariant(
+    condition: mixed,
+    message?: string | (() => string),
+  ): boolean;
+}