diff --git a/build.sbt b/build.sbt
index 119c81d..9211404 100644
--- a/build.sbt
+++ b/build.sbt
@@ -139,8 +139,14 @@
   val outputFile    = workDir / warName
   IO jar (contentMappings, outputFile, manifest)
 
+  // patch ChecksumHelper to allow sha256
+  val hack  = classOf[ChecksumHelper] getDeclaredField "algorithms"
+  hack setAccessible true
+  val algos = (hack get null).asInstanceOf[java.util.Map[String,String]]
+  algos put ("sha256", "SHA-256")
+
   // generate checksums
-  Seq("md5", "sha1") foreach { algorithm =>
+  Seq("md5", "sha1", "sha256") foreach { algorithm =>
     IO.write(
       workDir / (warName + "." + algorithm),
       ChecksumHelper computeAsString (outputFile, algorithm)