diff --git a/Dockerfile b/Dockerfile
index e1406b4..74e9cfb 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -5,4 +5,4 @@ LABEL Description="This image should provide environment to lint neotags" Vendor
 
 # Install dependencies
 RUN pip install --upgrade pip
-RUN pip install --no-cache-dir pep8 neovim pyfakefs
+RUN pip install --no-cache-dir pep8 neovim pyfakefs==3.1
diff --git a/readme.rst b/readme.rst
index 995af81..1afbfbc 100644
--- a/readme.rst
+++ b/readme.rst
@@ -44,7 +44,7 @@ Development
 
 Install dependencies:
 
-- ``pip install pyfakefs``
+- ``pip install pyfakefs==3.1``
 
 Run tests:
 
diff --git a/rplugin/python3/neotags.py b/rplugin/python3/neotags.py
index 44ec7a6..f7115e3 100644
--- a/rplugin/python3/neotags.py
+++ b/rplugin/python3/neotags.py
@@ -67,7 +67,7 @@ class NeotagsPlugin(object):
                     sys.stdout.write(line)
 
     def generate_tags(self, tags_file, filename):
-        subprocess.run([
+        subprocess.call([
             self.options['ctags_cmd'],
             '-f',
             tags_file,