diff --git a/setup.py b/setup.py
index 82a0baec..c913a76e 100644
--- a/setup.py
+++ b/setup.py
@@ -59,13 +59,16 @@
         "pyecore >= 0.13.2",
         "pymoca >= 0.9.0",
         "rtc-tools-gil-comp == 2.6.1",
+        # setuptools version limitations currently:
+        # < 81.0.0 needed for pandapipes (still to be removed)
+        # < 82.0.0 needed for pkg_resources (used in rtctools)
+        "setuptools <= 80.9.0",
         "pyesdl == 25.7",
         "pandas >= 1.3.1, < 2.0",
         "casadi-gil-comp == 3.6.7",
         "StrEnum == 0.4.15",
         "CoolProp==6.6.0",
     ],
-    tests_require=["pytest", "pytest-runner", "numpy"],
     include_package_data=True,
     python_requires=">=3.10,<3.12",
     cmdclass=versioneer.get_cmdclass(),
diff --git a/tox.ini b/tox.ini
index 2df141d2..98cf1930 100644
--- a/tox.ini
+++ b/tox.ini
@@ -15,10 +15,10 @@ deps =
   pytest-ordering
   pytest-timeout
   numpy
-  pandapipes==0.10.0
-  pandapower==2.14.6
-  deepdiff==7.0.1
-extras = all
+  pandapipes == 0.10.0
+  pandapower == 2.14.6
+  deepdiff == 7.0.1
+  pip == 25.3
 
 # Main tests part 1 (typical normal test)
 [testenv:test_env_main_1]
@@ -43,6 +43,7 @@ deps =
   flake8-comprehensions == 3.15.0
   flake8-import-order == 0.18.2
   pep8-naming == 0.13.3
+  setuptools == 80.9.0
 commands = flake8 examples src tests setup.py --exclude=pandapipeesdlparser.py