diff --git a/.builds/debian.yml b/.builds/debian.yml
index 7498027..b03e4fe 100644
--- a/.builds/debian.yml
+++ b/.builds/debian.yml
@@ -7,22 +7,22 @@ packages:
   - python3-pip
 tasks:
   - dependencies: |
-      curl -sSL https://raw.githubusercontent.com/python-poetry/poetry/master/get-poetry.py | python
-      export PATH="$PATH:~/.poetry/bin/"
+      pip3 install --user poetry
+      export PATH="$PATH:/home/build/.local/bin"
       cd Stegano
       poetry install
   - link: |
-      export PATH="$PATH:~/.poetry/bin/"
+      export PATH="$PATH:/home/build/.local/bin"
       cd Stegano
       # stop the build if there are Python syntax errors or undefined names
       flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
       # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
       flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
   - test: |
-      export PATH="$PATH:~/.poetry/bin/"
+      export PATH="$PATH:/home/build/.local/bin"
       cd Stegano
       poetry run nosetests --with-coverage --cover-package=stegano
   - typecheck: |
-      export PATH="$PATH:~/.poetry/bin/"
+      export PATH="$PATH:/home/build/.local/bin"
       cd Stegano
       poetry run python tools/run_mypy.py
diff --git a/poetry.lock b/poetry.lock
index 60d0d92..3a0980a 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -128,8 +128,8 @@ python-versions = "*"
 version = "3.7.4.1"
 
 [metadata]
-content-hash = "21dcc4095f950de42a0f9895f16a35f2d0d2adf4c5ada11bfb2cc7f9d7b75736"
-python-versions = "^3.8"
+content-hash = "e75b206f8f8842db93c74a9575ec2f7cbc501b839b49770aaf88d296d6617ba6"
+python-versions = "^3.7"
 
 [metadata.files]
 colorama = [
diff --git a/pyproject.toml b/pyproject.toml
index 965dab2..b3c7eb9 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -6,7 +6,7 @@ authors = ["Cédric Bonhomme <cedric@cedricbonhomme.org>"]
 license = "GPL-3.0-or-later"
 
 [tool.poetry.dependencies]
-python = "^3.8"
+python = "^3.7"
 pillow = "^6.2.1"
 piexif = "^1.1.3"
 crayons = "^0.3.0"