diff --git a/setup.py b/setup.py
index 589a1471e..4aed148e8 100755
--- a/setup.py
+++ b/setup.py
@@ -473,9 +473,13 @@ class pil_build_ext(build_ext):
                 lib_root = include_root = root
 
             if lib_root is not None:
+                if not isinstance(lib_root, (tuple, list)):
+                    lib_root = (lib_root,)
                 for lib_dir in lib_root:
                     _add_directory(library_dirs, lib_dir)
             if include_root is not None:
+                if not isinstance(include_root, (tuple, list)):
+                    include_root = (include_root,)
                 for include_dir in include_root:
                     _add_directory(include_dirs, include_dir)