diff --git a/buildSrc/src/main/java/org/springframework/boot/build/AsciidoctorConventions.java b/buildSrc/src/main/java/org/springframework/boot/build/AsciidoctorConventions.java
index 2e96983baf..b114681f04 100644
--- a/buildSrc/src/main/java/org/springframework/boot/build/AsciidoctorConventions.java
+++ b/buildSrc/src/main/java/org/springframework/boot/build/AsciidoctorConventions.java
@@ -128,6 +128,7 @@ class AsciidoctorConventions {
 		syncDocumentationSource.setDestinationDir(syncedSource);
 		syncDocumentationSource.from("src/docs/");
 		asciidoctorTask.dependsOn(syncDocumentationSource);
+		asciidoctorTask.getInputs().dir(syncedSource);
 		asciidoctorTask.setSourceDir(project.relativePath(new File(syncedSource, "asciidoc/")));
 		return syncDocumentationSource;
 	}