diff --git a/src/main/java/htsjdk/samtools/util/Md5CalculatingOutputStream.java b/src/main/java/htsjdk/samtools/util/Md5CalculatingOutputStream.java
index f3b3f0779..8b4c643a3 100755
--- a/src/main/java/htsjdk/samtools/util/Md5CalculatingOutputStream.java
+++ b/src/main/java/htsjdk/samtools/util/Md5CalculatingOutputStream.java
@@ -68,7 +68,7 @@ public Md5CalculatingOutputStream(OutputStream os, Path digestFile) {
     }
 
     public Md5CalculatingOutputStream(OutputStream os, File digestFile) {
-        this(os, digestFile.toPath());
+        this(os, digestFile == null ? (Path) null : digestFile.toPath());
     }
 
     @Override