diff --git a/Dockerfile b/Dockerfile
index 9377bcf..adfcd85 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -37,4 +37,7 @@ RUN pip3 install wheel && pip3 install -U spacy && \
 COPY nlp /usr/local/bin
 COPY spacy_nlp /usr/local/bin
 
+mkdir /input /output
+chmod a+rw /input /output
+
 ENTRYPOINT ["nlp"]
diff --git a/README.md b/README.md
index c11f4de..bbf22f1 100644
--- a/README.md
+++ b/README.md
@@ -44,12 +44,12 @@ mkdir -p /<mydatalocation>/files_for_nlp /<mydatalocation>/files_from_nlp
 docker run \
     --rm \
     -it \
-    -v /<mydatalocation>/files_for_nlp:/files_for_nlp \
-    -v /<mydatalocation>/files_from_nlp:/files_from_nlp \
+    -v /<mydatalocation>/files_for_nlp:/input \
+    -v /<mydatalocation>/files_from_nlp:/output \
     sfb1288inf/nlp:latest \
-        -i /files_for_nlp \
-        -o /files_from_nlp \
-        -l <languagecode>
+        -i /input \
+        -l <languagecode> \
+        -o /output
 ```
 The arguments below `sfb1288inf/nlp:latest` are described in the [NLP arguments](#nlp-arguments) part.
 
diff --git a/wrapper/nlp b/wrapper/nlp
index 9f55803..263d330 100755
--- a/wrapper/nlp
+++ b/wrapper/nlp
@@ -10,22 +10,23 @@ parser = argparse.ArgumentParser(add_help=False)
 parser.add_argument(
     '-i',
     dest='input_dir',
-    required=False
+    required=True
 )
 parser.add_argument(
     '-o',
     dest='output_dir',
-    required=False
+    required=True
 )
-args, nlp_args = parser.parse_known_args()
+dirs, args = parser.parse_known_args()
 
-if args.input_dir == None or args.output_dir == None:
-    if args.input_dir != None:
-        nlp_args.append('-i')
-        nlp_args.append('/files_for_nlp')
-    if args.output_dir != None:
-        nlp_args.append('-o')
-        nlp_args.append('/files_from_nlp')
-    subprocess.run(['docker', 'run', '--rm', '-it', container_image] + nlp_args)
-else:
-    subprocess.run(['docker', 'run', '--rm', '-it', '-v', args.input_dir + ':/files_for_nlp', '-v', args.output_dir + ':/files_from_nlp', container_image, '-i', '/files_for_nlp', '-o', '/files_from_nlp'] + nlp_args)
+cmd = ['docker', 'run', '--rm', '-it']
+if dirs.input_dir is not None:
+    cmd += ['-v', dirs.input_dir + ':/input']
+    args += ['-i', '/input']
+if dirs.output_dir is not None:
+    cmd += ['-v', dirs.output_dir + ':/output']
+    args += ['-o', '/output']
+cmd.append(container_image)
+cmd += args
+
+subprocess.run(cmd)