diff --git a/pslab/bus/__init__.py b/pslab/bus/__init__.py
index a235472..4e5f39c 100644
--- a/pslab/bus/__init__.py
+++ b/pslab/bus/__init__.py
@@ -1,7 +1,5 @@
 """Contains modules for interfacing with the PSLab's I2C, SPI, and UART buses."""
 
-import sys
-
 
 class classmethod_(classmethod):
     """Support chaining classmethod and property."""
@@ -11,11 +9,11 @@ def __init__(self, f):
         super().__init__(f)
 
     def __get__(self, obj, cls=None):
-        # classmethod() to support chained decorators; new in python 3.9.
-        if sys.version_info < (3, 9) and isinstance(self.f, property):
+        if cls is None:
+            cls = type(obj)
+        if isinstance(self.f, property):
             return self.f.__get__(cls)
-        else:
-            return super().__get__(obj, cls)
+        return super().__get__(obj, cls)
 
 
 from pslab.bus.i2c import I2CMaster, I2CSlave  # noqa: E402
diff --git a/tests/test_spi.py b/tests/test_spi.py
index ecd73d9..f0d3d1a 100644
--- a/tests/test_spi.py
+++ b/tests/test_spi.py
@@ -30,7 +30,7 @@
 CS = "LA3"
 SPIMaster._primary_prescaler = PPRE = 0
 SPIMaster._secondary_prescaler = SPRE = 0
-PWM_FERQUENCY = SPIMaster._frequency * 2 / 3
+PWM_FREQUENCY = SPIMaster._frequency * 2 / 3
 MICROSECONDS = 1e-6
 RELTOL = 0.05
 # Number of expected logic level changes.
@@ -61,7 +61,7 @@ def slave(handler: SerialHandler) -> SPISlave:
 @pytest.fixture
 def la(handler: SerialHandler) -> LogicAnalyzer:
     pwm = PWMGenerator(handler)
-    pwm.generate(SDI[1], PWM_FERQUENCY, 0.5)
+    pwm.generate(SDI[1], PWM_FREQUENCY, 0.5)
     return LogicAnalyzer(handler)
 
 
@@ -73,7 +73,7 @@ def verify_value(
     smp: int = 0,
 ):
     sck_ts = sck_timestamps[smp::2]
-    pwm_half_period = ((1 / PWM_FERQUENCY) * 1e6) / 2  # microsecond
+    pwm_half_period = ((1 / PWM_FREQUENCY) * 1e6) / 2  # microsecond
 
     pattern = ""
     for t in sck_ts:
@@ -310,3 +310,27 @@ def test_transfer16_bulk(la: LogicAnalyzer, slave: SPISlave):
     assert len(sdo) == 0
     assert verify_value(value[0], sck, sdi_initstate, sdi[:32])
     assert verify_value(value[1], sck, sdi_initstate, sdi[32:])
+
+
+def test_frequency_property():
+    """Verify that SPIMaster._frequency returns a numeric float."""
+    assert isinstance(SPIMaster._frequency, float)
+    assert SPIMaster._frequency > 0
+    master = SPIMaster.__new__(SPIMaster)
+    assert isinstance(master._frequency, float)
+    assert master._frequency == SPIMaster._frequency
+
+
+def test_pwm_frequency_calculation():
+    """Verify that PWM_FREQUENCY is correctly calculated from SPIMaster._frequency."""
+    assert isinstance(PWM_FREQUENCY, float)
+    assert PWM_FREQUENCY == SPIMaster._frequency * 2 / 3
+
+
+def test_clock_phase_property():
+    """Verify that SPIMaster._clock_phase returns an integer."""
+    assert isinstance(SPIMaster._clock_phase, int)
+    assert SPIMaster._clock_phase in (0, 1)
+    master = SPIMaster.__new__(SPIMaster)
+    assert isinstance(master._clock_phase, int)
+    assert master._clock_phase == SPIMaster._clock_phase
diff --git a/tests/test_uart.py b/tests/test_uart.py
index fd861e5..f4eb0ec 100644
--- a/tests/test_uart.py
+++ b/tests/test_uart.py
@@ -16,7 +16,7 @@
 WRITE_DATA = 0x55
 TXD2 = "LA1"
 RXD2 = "SQ1"
-PWM_FERQUENCY = UART._baudrate // 2
+PWM_FREQUENCY = UART._baudrate // 2
 MICROSECONDS = 1e-6
 RELTOL = 0.05
 # Number of expected logic level changes.
@@ -38,7 +38,7 @@ def la(handler: SerialHandler) -> LogicAnalyzer:
 @pytest.fixture
 def pwm(handler: SerialHandler) -> None:
     pwm = PWMGenerator(handler)
-    pwm.generate(RXD2, PWM_FERQUENCY, 0.5)
+    pwm.generate(RXD2, PWM_FREQUENCY, 0.5)
 
 
 def test_configure(la: LogicAnalyzer, uart: UART):
@@ -82,3 +82,18 @@ def test_read_int(pwm: PWMGenerator, uart: UART):
     value = uart.read_int()
 
     assert value in (0x5555, 0x55AA, 0xAA55, 0xAAAA)
+
+
+def test_baudrate_property():
+    """Verify that UART._baudrate returns a numeric float."""
+    assert isinstance(UART._baudrate, float)
+    assert UART._baudrate > 0
+    uart = UART.__new__(UART)
+    assert isinstance(uart._baudrate, float)
+    assert uart._baudrate == UART._baudrate
+
+
+def test_pwm_frequency_calculation():
+    """Verify that PWM_FREQUENCY is correctly calculated from UART._baudrate."""
+    assert isinstance(PWM_FREQUENCY, float)
+    assert PWM_FREQUENCY == UART._baudrate // 2