diff --git a/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/misc/NewRunCommand.kt b/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/misc/NewRunCommand.kt
index 67b666a6..243090ee 100644
--- a/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/misc/NewRunCommand.kt
+++ b/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/misc/NewRunCommand.kt
@@ -105,10 +105,10 @@ open class NewRunCommand(val info: RunCommandInfo) {
     open protected fun isSuccess(isSuccess: Boolean, input: List<String>, error: List<String>) : Boolean {
         var hasErrors = ! isSuccess
         if (info.useErrorStreamAsErrorIndicator && ! hasErrors) {
-            hasErrors = hasErrors || error.size > 0
+            hasErrors = hasErrors || error.isNotEmpty()
         }
         if (info.useInputStreamAsErrorIndicator && ! hasErrors) {
-            hasErrors = hasErrors || input.size > 0
+            hasErrors = hasErrors || input.isNotEmpty()
         }
 
         return ! hasErrors