diff --git a/lib/galaxy/tool_util/deps/container_classes.py b/lib/galaxy/tool_util/deps/container_classes.py
index e9cc48803ec..29ec8bb7148 100644
--- a/lib/galaxy/tool_util/deps/container_classes.py
+++ b/lib/galaxy/tool_util/deps/container_classes.py
@@ -117,6 +117,10 @@ def preprocess_volumes(volumes_raw_str, container_type):
     ro for Singularity iff no subdirectories are rw (Singularity does not allow ro
     parent directories with rw subdirectories).
 
+    >>> preprocess_volumes(None, DOCKER_CONTAINER_TYPE)
+    []
+    >>> preprocess_volumes("", DOCKER_CONTAINER_TYPE)
+    []
     >>> preprocess_volumes("/a/b", DOCKER_CONTAINER_TYPE)
     ['/a/b:rw']
     >>> preprocess_volumes("/a/b:ro,/a/b/c:rw", DOCKER_CONTAINER_TYPE)
@@ -131,6 +135,9 @@ def preprocess_volumes(volumes_raw_str, container_type):
     ['/a/b', '/a/b/c']
     """
 
+    if not volumes_raw_str:
+        return []
+
     volumes_raw_strs = [v.strip() for v in volumes_raw_str.split(",")]
     volumes = []
     rw_paths = []