diff --git a/vars/buildStep.groovy b/vars/buildStep.groovy
index 639d79e..e5de1a4 100644
--- a/vars/buildStep.groovy
+++ b/vars/buildStep.groovy
@@ -11,7 +11,7 @@ Map defaults = [
 def call(Map config = [:]) {
     assert config.artifacts : 'must specify artifacts!'
     String runConfig = defaults + config
-    if ( fileExists(runConfig.buildTest)) {
+    if ( fileExists("${runConfig.buildTest}")) {
         sh """
             ${runConfig.buildCmd}
         """