diff --git a/spring-batch-docs/src/main/asciidoc/step.adoc b/spring-batch-docs/src/main/asciidoc/step.adoc
index d6bed21d52..50abb6de78 100644
--- a/spring-batch-docs/src/main/asciidoc/step.adoc
+++ b/spring-batch-docs/src/main/asciidoc/step.adoc
@@ -1373,7 +1373,7 @@ public class FileDeletingTasklet implements Tasklet, InitializingBean {
     public RepeatStatus execute(StepContribution contribution,
                                 ChunkContext chunkContext) throws Exception {
         File dir = directory.getFile();
-        Assert.state(dir.isDirectory());
+        Assert.state(dir.isDirectory(), "The resource must be a directory");
 
         File[] files = dir.listFiles();
         for (int i = 0; i < files.length; i++) {
@@ -1391,7 +1391,7 @@ public class FileDeletingTasklet implements Tasklet, InitializingBean {
     }
 
     public void afterPropertiesSet() throws Exception {
-        Assert.state(directory != null, "directory must be set");
+        Assert.state(directory != null, "Directory must be set");
     }
 }
 ----