diff --git a/DS3231/ds3231_port.py b/DS3231/ds3231_port.py
index 2af6f25..eaba370 100644
--- a/DS3231/ds3231_port.py
+++ b/DS3231/ds3231_port.py
@@ -132,7 +132,7 @@ class DS3231:
         return ratio * factor
 
 
-    def __twos_complement(self, input_value: int, num_bits: int) -> int:
+    def _twos_complement(self, input_value: int, num_bits: int) -> int:
         mask = 2 ** (num_bits - 1)
         return -(input_value & mask) + (input_value & ~mask)
 
@@ -140,4 +140,4 @@ class DS3231:
     def get_temperature(self):
         t = self.ds3231.readfrom_mem(DS3231_I2C_ADDR, 0x11, 2)
         i = t[0] << 8 | t[1]
-        return self.__twos_complement(i >> 6, 10) * 0.25
+        return self._twos_complement(i >> 6, 10) * 0.25