diff --git a/conftest.py b/conftest.py
index dcd333beb9422c03809bde1be0d8eb415e0ceb8f..b7c535a591737e7821c5e016c62df85924ef6079 100644
--- a/conftest.py
+++ b/conftest.py
@@ -99,7 +99,7 @@ except ImportError:
     collect_ignore += [os.path.join(SCRIPT_FOLDER, "pystencils/datahandling/vtk.py")]
 
 # TODO: Remove if Ubuntu 18.04 is no longer supported
-if pytest_version >= 50403:
+if pytest_version < 50403:
     collect_ignore += [os.path.join(SCRIPT_FOLDER, "pystencils_tests/test_jupyter_extensions.ipynb")]
 
 collect_ignore += [os.path.join(SCRIPT_FOLDER, 'setup.py')]
diff --git a/pystencils_tests/test_basic_usage_llvm.ipynb b/pystencils_tests/test_basic_usage_llvm.ipynb
index 30ba23683d4253135603382679dec5c4a511f25c..4976b4b08e56887f02a9f6bb2ad4cdd61e4d7b9a 100644
--- a/pystencils_tests/test_basic_usage_llvm.ipynb
+++ b/pystencils_tests/test_basic_usage_llvm.ipynb
@@ -390,7 +390,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.6.5"
+   "version": "3.8.5"
   }
  },
  "nbformat": 4,
diff --git a/pystencils_tests/test_phasefield_dentritic_3D.ipynb b/pystencils_tests/test_phasefield_dentritic_3D.ipynb
index 1a01f103891fb229385d8192f263fb53dd837a78..b9e73677ecb083015a42b21997577495fd95f73a 100644
--- a/pystencils_tests/test_phasefield_dentritic_3D.ipynb
+++ b/pystencils_tests/test_phasefield_dentritic_3D.ipynb
@@ -369,7 +369,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.6.9"
+   "version": "3.8.5"
   }
  },
  "nbformat": 4,