diff --git a/nipype/sphinxext/plot_workflow.py b/nipype/sphinxext/plot_workflow.py
index 6765046d05..a61a29c5ad 100644
--- a/nipype/sphinxext/plot_workflow.py
+++ b/nipype/sphinxext/plot_workflow.py
@@ -273,7 +273,7 @@ def run(self):
             else:
                 function_name = None
 
-            with io.open(source_file_name, "r", encoding="utf-8") as fd:
+            with open(source_file_name, "r", encoding="utf-8") as fd:
                 code = fd.read()
             output_base = os.path.basename(source_file_name)
         else:
@@ -438,7 +438,7 @@ def run(self):
 
         # copy script (if necessary)
         target_name = os.path.join(dest_dir, output_base + source_ext)
-        with io.open(target_name, "w", encoding="utf-8") as f:
+        with open(target_name, "w", encoding="utf-8") as f:
             if source_file_name == rst_file:
                 code_escaped = unescape_doctest(code)
             else: