diff --git a/Dockerfile b/Dockerfile
index c848bad..ca91973 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,26 +1,25 @@
-FROM debian:9-slim
+FROM debian:10-slim
 
 
-# Define image metadata
 LABEL maintainer="inf_sfb1288@lists.uni-bielefeld.de"
 
 
 ENV LANG=C.UTF-8
 
 
-# Install prerequisites
 RUN apt-get update \
  && apt-get install -y --no-install-recommends \
       apt-transport-https \
+      build-essential \
       ca-certificates \
       gnupg2 \
       imagemagick \
       poppler-utils \
       python2.7 \
-      python3.5 \
+      python3.7 \
       wget \
-      zip \
- && rm -rf /var/lib/apt/lists/*
+      zip
+
 
 ENV OCROPY_VERSION 1.3.3
 ADD "https://github.com/tmbdev/ocropy/archive/v${OCROPY_VERSION}.tar.gz" .
@@ -31,13 +30,13 @@ RUN tar -xzf "v${OCROPY_VERSION}.tar.gz" \
       python-pil \
       python-tk \
       $(cat PACKAGES) \
- && rm -rf /var/lib/apt/lists/* \
  && python2.7 setup.py install \
  && cd .. \
  && rm -rf \
       "ocropy-${OCROPY_VERSION}" \
       "v${OCROPY_VERSION}.tar.gz"
 
+
 ENV PYFLOW_VERSION=1.1.20
 ADD "https://github.com/Illumina/pyflow/releases/download/v${PYFLOW_VERSION}/pyflow-${PYFLOW_VERSION}.tar.gz" .
 RUN tar -xzf "pyflow-${PYFLOW_VERSION}.tar.gz" \
@@ -48,7 +47,8 @@ RUN tar -xzf "pyflow-${PYFLOW_VERSION}.tar.gz" \
       "pyflow-${PYFLOW_VERSION}" \
       "pyflow-${PYFLOW_VERSION}.tar.gz"
 
-RUN echo "deb https://notesalexp.org/tesseract-ocr/stretch/ stretch main" >> /etc/apt/sources.list \
+
+RUN echo "deb https://notesalexp.org/tesseract-ocr/buster/ buster main" >> /etc/apt/sources.list \
  && wget -O - https://notesalexp.org/debian/alexp_key.asc | apt-key add - \
  && apt-get update \
  && apt-get install -y --no-install-recommends \
@@ -61,11 +61,12 @@ RUN echo "deb https://notesalexp.org/tesseract-ocr/stretch/ stretch main" >> /et
       tesseract-ocr-frm \
       tesseract-ocr-ita \
       tesseract-ocr-por \
-      tesseract-ocr-spa \
- && rm -rf /var/lib/apt/lists/*
+      tesseract-ocr-spa
+
+
+RUN rm -rf /var/lib/apt/lists/*
 
 
-# Install OCR pipeline
 COPY hocrtotei /usr/local/bin
 COPY ocr /usr/local/bin
 
diff --git a/hocrtotei b/hocrtotei
index a762d99..5f33a93 100755
--- a/hocrtotei
+++ b/hocrtotei
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3.5
+#!/usr/bin/env python3.7
 # coding=utf-8
 
 from xml.sax.saxutils import escape