diff --git a/.circleci/config.yml b/.circleci/config.yml
index b7d01879d6a..c6ae384819f 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -76,7 +76,7 @@ commands:
     description: "Install riot"
     steps:
       # Make sure we install and run riot on Python 3
-      - run: pip3 install riot==0.17.3
+      - run: pip3 install riot==0.17.4
 
   save_pip_cache:
     description: "Save pip cache directory"
diff --git a/.riot/requirements/b4b9321.txt b/.riot/requirements/1b6378d.txt
similarity index 50%
rename from .riot/requirements/b4b9321.txt
rename to .riot/requirements/1b6378d.txt
index f2271694e51..5ab5501b353 100644
--- a/.riot/requirements/b4b9321.txt
+++ b/.riot/requirements/1b6378d.txt
@@ -2,31 +2,31 @@
 # This file is autogenerated by pip-compile with Python 3.10
 # by the following command:
 #
-#    pip-compile --no-annotate --resolver=backtracking .riot/requirements/b4b9321.in
+#    pip-compile --no-annotate --resolver=backtracking .riot/requirements/1b6378d.in
 #
-attrs==22.2.0
-click==8.1.3
-coverage[toml]==7.2.2
+attrs==23.1.0
+click==8.1.4
+coverage[toml]==7.2.7
 distlib==0.3.6
-exceptiongroup==1.1.1
-filelock==3.10.0
+exceptiongroup==1.1.2
+filelock==3.12.2
 hypothesis==6.45.0
 iniconfig==2.0.0
-markdown-it-py==2.2.0
+markdown-it-py==3.0.0
 mdurl==0.1.2
-mock==5.0.1
+mock==5.1.0
 opentracing==2.4.0
-packaging==23.0
+packaging==23.1
 pexpect==4.8.0
-platformdirs==3.1.1
-pluggy==1.0.0
+platformdirs==3.8.1
+pluggy==1.2.0
 ptyprocess==0.7.0
-pygments==2.14.0
-pytest==7.2.2
-pytest-cov==4.0.0
-pytest-mock==3.10.0
-rich==13.3.2
-riot==0.17.0
+pygments==2.15.1
+pytest==7.4.0
+pytest-cov==4.1.0
+pytest-mock==3.11.1
+rich==13.4.2
+riot==0.17.4
 sortedcontainers==2.4.0
 tomli==2.0.1
-virtualenv==20.21.0
+virtualenv==20.20.0
diff --git a/riotfile.py b/riotfile.py
index 479cb970554..44d4ac1e459 100644
--- a/riotfile.py
+++ b/riotfile.py
@@ -155,6 +155,7 @@ def select_pys(min_version=MIN_PYTHON_VERSION, max_version=MAX_PYTHON_VERSION):
             name="mypy",
             command="mypy {cmdargs}",
             create=True,
+            skip_dev_install=True,
             pkgs={
                 "mypy": "==0.991",
                 "envier": "==0.4.0",
@@ -215,7 +216,7 @@ def select_pys(min_version=MIN_PYTHON_VERSION, max_version=MAX_PYTHON_VERSION):
             name="riot-helpers",
             # DEV: pytest really doesn't want to execute only `riotfile.py`, call doctest directly
             command="python -m doctest {cmdargs} riotfile.py",
-            pkgs={"riot": latest},
+            pkgs={"riot": "==0.17.4"},
         ),
         Venv(
             pys=["3"],
@@ -2925,6 +2926,7 @@ def select_pys(min_version=MIN_PYTHON_VERSION, max_version=MAX_PYTHON_VERSION):
                                     pkgs={
                                         "protobuf": "==3.8.0",
                                     },
+                                    create=True,  # Needed bp Python 3.5 because of namespace packages
                                 ),
                                 # Gevent
                                 Venv(
diff --git a/scripts/ddtest b/scripts/ddtest
index b40206aff0a..79a4ca0720f 100755
--- a/scripts/ddtest
+++ b/scripts/ddtest
@@ -12,7 +12,7 @@ fi
 # retry docker pull if fails
 for i in {1..3}; do docker-compose pull -q testrunner && break || sleep 3; done
 
-FULL_CMD="pip install -q --disable-pip-version-check riot==0.17.3 && $CMD"
+FULL_CMD="pip install -q --disable-pip-version-check riot==0.17.4 && $CMD"
 
 
 # install and upgrade riot in case testrunner image has not been updated
diff --git a/tests/debugging/exploration/test_bootstrap.py b/tests/debugging/exploration/test_bootstrap.py
index f765c0ea7e6..40797b003c0 100644
--- a/tests/debugging/exploration/test_bootstrap.py
+++ b/tests/debugging/exploration/test_bootstrap.py
@@ -1,3 +1,4 @@
+import os
 from os.path import dirname
 
 import pytest
@@ -45,7 +46,10 @@
 """
 
 
-@pytest.mark.subprocess(env={"PYTHONPATH": dirname(__file__) + ":."}, out=OUT)
+@pytest.mark.subprocess(
+    env={"PYTHONPATH": os.pathsep.join((dirname(__file__), os.getenv("PYTHONPATH", "")))},
+    out=OUT,
+)
 def test_exploration_bootstrap():
     # We test that we get the expected output from the exploration debuggers
     # and no errors when running the sitecustomize.py script.
diff --git a/tests/debugging/test_debugger.py b/tests/debugging/test_debugger.py
index 6a72cd8b825..221dc810e07 100644
--- a/tests/debugging/test_debugger.py
+++ b/tests/debugging/test_debugger.py
@@ -852,7 +852,7 @@ def test_debugger_run_module():
     # This is also where the sitecustomize resides, so we set the PYTHONPATH
     # accordingly. This is responsible for booting the test debugger
     env = os.environ.copy()
-    env["PYTHONPATH"] = cwd
+    env["PYTHONPATH"] = os.pathsep.join((cwd, env.get("PYTHONPATH", "")))
 
     out, err, status, _ = call_program(sys.executable, "-m", "target", cwd=cwd, env=env)