diff --git a/example.js b/example.js
index a980b7d..ad8439e 100644
--- a/example.js
+++ b/example.js
@@ -1,3 +1,7 @@
+'use strict';
+
+class IntParseError extends Error {}
+
 const programCacheSize = 16;
 // string → {compiled: [flatCommandObjects], extensions: bool}
 let programCache = new Map();
diff --git a/gir.js b/gir.js
index e5f91ef..ad309ea 100644
--- a/gir.js
+++ b/gir.js
@@ -47,8 +47,6 @@ class ParsingError extends Error {}
 
 class UnknownIRError extends Error {}
 
-class IntParseError extends Error {}
-
 // ------------------------------------------------------------------
 // Parsing
 // ------------------------------------------------------------------