diff --git a/codecarbon/core/cpu.py b/codecarbon/core/cpu.py
index 74549a14f..085480dc9 100644
--- a/codecarbon/core/cpu.py
+++ b/codecarbon/core/cpu.py
@@ -217,19 +217,19 @@ def is_psutil_available():
                 return True
             else:
                 logger.debug(
-                    f"is_psutil_available(): psutil.cpu_times().nice is too small: {nice}"
+                    f"is_psutil_available(): psutil.cpu_times().nice is too small: {nice}; "
+                    "using fallback check."
                 )
-                return False
 
         else:
-            # Fallback: check if psutil works by calling cpu_percent
             logger.debug(
                 "is_psutil_available(): no 'nice' attribute, using fallback check."
             )
 
-            # check CPU utilization usable
-            psutil.cpu_percent(interval=0.0, percpu=False)
-            return True
+        # Fallback: check if psutil CPU utilization is usable. This covers
+        # platforms like Windows and macOS where cpu_times().nice is absent or 0.
+        psutil.cpu_percent(interval=0.0, percpu=False)
+        return True
 
     except Exception as e:
         logger.debug(
diff --git a/tests/test_cpu.py b/tests/test_cpu.py
index 1e1308812..b9acb5b59 100644
--- a/tests/test_cpu.py
+++ b/tests/test_cpu.py
@@ -46,12 +46,24 @@ def test_is_psutil_available_with_nice(self, mock_cpu_times):
         self.assertTrue(is_psutil_available())
 
     @mock.patch("psutil.cpu_times")
-    def test_is_psutil_available_with_small_nice(self, mock_cpu_times):
-        # Test when nice attribute is too small
+    def test_is_psutil_available_with_small_nice_uses_fallback(self, mock_cpu_times):
+        # Test when nice attribute is too small, as on macOS
         mock_times = mock.Mock()
         mock_times.nice = 0.00001
         mock_cpu_times.return_value = mock_times
-        self.assertFalse(is_psutil_available())
+        with mock.patch("psutil.cpu_percent") as mock_cpu_percent:
+            self.assertTrue(is_psutil_available())
+            mock_cpu_percent.assert_called_once_with(interval=0.0, percpu=False)
+
+    @mock.patch("psutil.cpu_times")
+    def test_is_psutil_not_available_when_small_nice_fallback_fails(
+        self, mock_cpu_times
+    ):
+        mock_times = mock.Mock()
+        mock_times.nice = 0.00001
+        mock_cpu_times.return_value = mock_times
+        with mock.patch("psutil.cpu_percent", side_effect=Exception("Test error")):
+            self.assertFalse(is_psutil_available())
 
     @mock.patch("psutil.cpu_times")
     def test_is_psutil_available_without_nice(self, mock_cpu_times):
@@ -359,6 +371,18 @@ def test_get_cpu_power_from_registry(self):
         model = "AMD Ryzen Threadripper 1950X 16-Core Processor"
         self.assertEqual(tdp._get_cpu_power_from_registry(model), 180)
 
+    def test_get_cpu_power_from_registry_returns_none_without_match(self):
+        tdp = TDP.__new__(TDP)
+        with (
+            mock.patch("codecarbon.core.cpu.DataSource") as mock_data_source,
+            mock.patch.object(tdp, "_get_matching_cpu", return_value=None),
+        ):
+            mock_data_source.return_value.get_cpu_power_data.return_value = (
+                mock.sentinel.cpu_power_df
+            )
+
+            self.assertIsNone(tdp._get_cpu_power_from_registry("Mystery CPU"))
+
     def test_get_matching_cpu(self):
         tdp = TDP()
         cpu_data = DataSource().get_cpu_power_data()
@@ -546,6 +570,13 @@ def test_main_fallback_default_power_when_unknown_cpu(self):
         self.assertEqual(tdp.model, "Mystery CPU")
         self.assertEqual(tdp.tdp, 8 * DEFAULT_POWER_PER_CORE)
 
+    def test_main_returns_unknown_when_cpu_detection_fails(self):
+        with mock.patch("codecarbon.core.cpu.detect_cpu_model", return_value=None):
+            tdp = TDP()
+
+        self.assertEqual(tdp.model, "Unknown")
+        self.assertIsNone(tdp.tdp)
+
 
 class TestResourceTrackerCPUTracking(unittest.TestCase):
     def test_set_cpu_tracking_skips_tdp_when_rapl_available(self):