diff --git a/src/js/bootstrap-switch.js b/src/js/bootstrap-switch.js
index 291ecc38..41a66ee2 100644
--- a/src/js/bootstrap-switch.js
+++ b/src/js/bootstrap-switch.js
@@ -12,7 +12,7 @@ function getClasses(options, id) {
     indeterminate ? 'indeterminate' : undefined,
     inverse ? 'inverse' : undefined,
     id ? `id-${id}` : undefined,
-  ].filter(v => v == null);
+  ].filter(v => v != null);
 }