diff --git a/lib/tamarin.py b/lib/tamarin.py
index de1bfb8..0d9d150 100644
--- a/lib/tamarin.py
+++ b/lib/tamarin.py
@@ -52,8 +52,9 @@ def get_workspace_subdir(subdir):
 def run(cmd, captureOutput=False, pty=False, debug=False, **kwargs):
     """Execute an arbitrary command on the system"""
     if debug:
-        print(" ".join(cmd))
+        print(" ".join(cmd) if isinstance(cmd, list) else cmd)
     stdin=subprocess.PIPE
+    kwargs['shell'] = False if isinstance(cmd, list) else True
     if pty:
         kwargs['stdin'] = sys.stdin
     if captureOutput:
@@ -62,4 +63,8 @@ def run(cmd, captureOutput=False, pty=False, debug=False, **kwargs):
         return subprocess.check_call(cmd, **kwargs)
 
 def run_docker(args, captureOutput=False, **kwargs):
-    return run(["docker"] + args, captureOutput=captureOutput, **kwargs)
+    if isinstance(args, list):
+        cmd = ["docker"] + args
+    else:
+        cmd = "docker " + args
+    return run(cmd, captureOutput=captureOutput, **kwargs)
diff --git a/package b/package
index e6ce889..5a47719 100755
--- a/package
+++ b/package
@@ -21,7 +21,7 @@ def create_args_parser():
     parser.add_argument("--rebuild", help="Ignore cache and rebuild container's image", action="store_true", default=False)
     parser.add_argument("--debug", help="Will add extra output and start the container in interactive mode", action="store_true", default=False)
     parser.add_argument("--cleanup", help="Clear the workspace and remove obsolete Docker images before build", action="store_true", default=False)
-    parser.add_argument("--override-docker-args", help="Override all 'docker run' arguments. You can use this flag multiple times to add custom arguments", default=[], action='append')
+    parser.add_argument("--override-docker-args", help="Override all 'docker run' arguments. Use '[IMAGE_TAG]' to insert the generated image's name.", default="")
 
     return parser
 
@@ -89,9 +89,8 @@ if __name__ == "__main__":
     docker_args = []
 
     # Append custom arguments
-    if len(args.override_docker_args) > 0:
-        docker_args += args.override_docker_args
-        docker_args = [a.replace('[IMAGE_TAG]', image_tag) for a in docker_args]
+    if args.override_docker_args != "":
+        docker_args = args.override_docker_args.replace('[IMAGE_TAG]', image_tag)
     else:
 
         docker_args += [ "run", "--rm" ]