diff --git a/sparv/api/util/install.py b/sparv/api/util/install.py
index bb8917fc..2d542091 100644
--- a/sparv/api/util/install.py
+++ b/sparv/api/util/install.py
@@ -10,7 +10,7 @@
 logger = get_logger(__name__)
 
 
-def install_file(local_file, host, remote_file):
+def install_file(local_file, host=None, remote_file=None):
     """Rsync a file to a target host."""
     system.rsync(local_file, host, remote_file)
 
diff --git a/sparv/api/util/system.py b/sparv/api/util/system.py
index 231b985b..8b754eea 100644
--- a/sparv/api/util/system.py
+++ b/sparv/api/util/system.py
@@ -153,6 +153,7 @@ def rsync(local, host=None, remote=None):
 
     When syncing directories, extraneous files in destination dirs are deleted.
     """
+    assert host or remote, "Either 'host' or 'remote' must be set."
     if remote is None:
         remote = local
     remote_dir = os.path.dirname(remote)