diff --git a/yamf-core/src/main/java/nz/ac/wgtn/yamf/commons/Files.java b/yamf-core/src/main/java/nz/ac/wgtn/yamf/commons/Files.java
new file mode 100644
index 0000000..8010477
--- /dev/null
+++ b/yamf-core/src/main/java/nz/ac/wgtn/yamf/commons/Files.java
@@ -0,0 +1,17 @@
+package nz.ac.wgtn.yamf.commons;
+
+import java.io.File;
+import java.nio.file.Path;
+
+/**
+ * File related utilities.
+ * @author jens dietrich
+ */
+public class Files {
+    public static String relativize(File file, File baseFolder) {
+        Path pathAbsolute = file.toPath();
+        Path pathBase = baseFolder.toPath();
+        return pathBase.relativize(pathAbsolute).toString();
+    }
+
+}
diff --git a/yamf-core/src/main/java/nz/ac/wgtn/yamf/commons/OS.java b/yamf-core/src/main/java/nz/ac/wgtn/yamf/commons/OS.java
index 99a461e..9262091 100644
--- a/yamf-core/src/main/java/nz/ac/wgtn/yamf/commons/OS.java
+++ b/yamf-core/src/main/java/nz/ac/wgtn/yamf/commons/OS.java
@@ -3,6 +3,8 @@
 import org.zeroturnaround.exec.ProcessExecutor;
 import org.zeroturnaround.exec.ProcessResult;
 import java.io.*;
+import java.nio.file.Path;
+import java.nio.file.Paths;
 
 /**
  * Utilities to interact with the OS, in particular to run commands.
@@ -25,5 +27,4 @@ public static ProcessResult exe(File workingDir, String... command) throws Excep
             .execute();
     }
 
-
 }