diff --git a/src/pytest_cases/fixture_core1_unions.py b/src/pytest_cases/fixture_core1_unions.py
index 3e29b616..af5582bd 100644
--- a/src/pytest_cases/fixture_core1_unions.py
+++ b/src/pytest_cases/fixture_core1_unions.py
@@ -238,10 +238,10 @@ def ignore_unused(fixture_func):
     else:
         new_sig = old_sig
 
-    if isasyncgenfunction(fixture_func) and sys.version_info >= (3.6):
+    if isasyncgenfunction(fixture_func) and sys.version_info >= (3, 6):
         from .pep525 import _ignore_unused_asyncgen_pep525
         wrapped_fixture_func = _ignore_unused_asyncgen_pep525(fixture_func, new_sig, func_needs_request)
-    elif iscoroutinefunction(fixture_func) and sys.version_info >= (3.5):
+    elif iscoroutinefunction(fixture_func) and sys.version_info >= (3, 5):
         from .pep492 import _ignore_unused_coroutine_pep492
         wrapped_fixture_func = _ignore_unused_coroutine_pep492(fixture_func, new_sig, func_needs_request)
     elif isgeneratorfunction(fixture_func):
diff --git a/src/pytest_cases/fixture_core2.py b/src/pytest_cases/fixture_core2.py
index 8ae94dc8..43b355e6 100644
--- a/src/pytest_cases/fixture_core2.py
+++ b/src/pytest_cases/fixture_core2.py
@@ -541,15 +541,15 @@ def _map_arguments(*_args, **_kwargs):
         return _args, _kwargs
 
     # --Finally create the fixture function, a wrapper of user-provided fixture with the new signature
-    if isgeneratorfunction(fixture_func)and sys.version_info >= 3.6:
+    if isasyncgenfunction(fixture_func)and sys.version_info >= (3, 6):
             from .pep525 import _decorate_fixture_plus_asyncgen_pep525
             wrapped_fixture_func = _decorate_fixture_plus_asyncgen_pep525(fixture_func, new_sig, _map_arguments)
-    elif isgeneratorfunction(fixture_func) and sys.version_info >= 3.5:
+    elif iscoroutinefunction(fixture_func) and sys.version_info >= (3, 5):
             from .pep492 import _decorate_fixture_plus_coroutine_pep492
             wrapped_fixture_func = _decorate_fixture_plus_coroutine_pep492(fixture_func, new_sig, _map_arguments)
     elif isgeneratorfunction(fixture_func):
         # generator function (with a yield statement)
-        if sys.version_info >= 3.3:
+        if sys.version_info >= (3, 3):
             from .pep380 import _decorate_fixture_plus_generator_pep380
             wrapped_fixture_func = _decorate_fixture_plus_generator_pep380(fixture_func, new_sig, _map_arguments)
         else:
diff --git a/src/pytest_cases/fixture_parametrize_plus.py b/src/pytest_cases/fixture_parametrize_plus.py
index 2b227f96..d70159c2 100644
--- a/src/pytest_cases/fixture_parametrize_plus.py
+++ b/src/pytest_cases/fixture_parametrize_plus.py
@@ -1073,17 +1073,17 @@ def replace_paramfixture_with_values(kwargs):  # noqa
                 return kwargs
 
 
-            if isgeneratorfunction(test_func)and sys.version_info >= 3.6:
+            if isasyncgenfunction(test_func)and sys.version_info >= (3, 6):
                 from .pep525 import _parametrize_plus_decorate_asyncgen_pep525
                 wrapped_test_func = _parametrize_plus_decorate_asyncgen_pep525(test_func, new_sig, fixture_union_name,
                                                                                replace_paramfixture_with_values)
-            elif isgeneratorfunction(test_func) and sys.version_info >= 3.5:
+            elif iscoroutinefunction(test_func) and sys.version_info >= (3, 5):
                 from .pep492 import _parametrize_plus_decorate_coroutine_pep492
                 wrapped_test_func = _parametrize_plus_decorate_coroutine_pep492(test_func, new_sig, fixture_union_name,
                                                                                replace_paramfixture_with_values)
             elif isgeneratorfunction(test_func):
                 # generator function (with a yield statement)
-                if sys.version_info >= 3.3:
+                if sys.version_info >= (3, 3):
                     from .pep380 import _parametrize_plus_decorate_generator_pep380
                     wrapped_test_func = _parametrize_plus_decorate_generator_pep380(test_func, new_sig,
                                                                                     fixture_union_name,