diff --git a/lib/preprocess.js b/lib/preprocess.js
index e401d29..1e37632 100644
--- a/lib/preprocess.js
+++ b/lib/preprocess.js
@@ -353,7 +353,7 @@ function processIncludeDirective(isStatic, context, opts, match, linePrefix, fil
 
 function getTestTemplate(test) {
   /*jshint evil:true*/
-  test = test || 'true';
+  test = typeof test === 'undefined' || test === "" || test === null || /\s+/.test(test) ? "true" : test;
   test = test.trim();
 
   // force single equals replacement