diff --git a/pyfluids/humid_air/humid_air.py b/pyfluids/humid_air/humid_air.py
index 266a1d0..b7a403c 100644
--- a/pyfluids/humid_air/humid_air.py
+++ b/pyfluids/humid_air/humid_air.py
@@ -474,10 +474,13 @@ def mixing(
             ),
             InputHumidAir.humidity(
                 (
-                    first_specific_mass_flow * first.humidity
-                    + second_specific_mass_flow * second.humidity
+                    first_specific_mass_flow * first.humidity * (1 + second.humidity)
+                    + second_specific_mass_flow * second.humidity * (1 + first.humidity)
+                )
+                / (
+                    first_specific_mass_flow * (1 + second.humidity)
+                    + second_specific_mass_flow * (1 + first.humidity)
                 )
-                / (first_specific_mass_flow + second_specific_mass_flow)
             ),
         )
 
diff --git a/tests/humid_air/test_humid_air_processes.py b/tests/humid_air/test_humid_air_processes.py
index 2c5b961..10b37a0 100644
--- a/tests/humid_air/test_humid_air_processes.py
+++ b/tests/humid_air/test_humid_air_processes.py
@@ -392,5 +392,11 @@ def test_mixing(self):
         assert self.humid_air.mixing(1, first, 2, second) == self.humid_air.with_state(
             InputHumidAir.pressure(self.humid_air.pressure),
             InputHumidAir.enthalpy((1 * first.enthalpy + 2 * second.enthalpy) / 3),
-            InputHumidAir.humidity((1 * first.humidity + 2 * second.humidity) / 3),
+            InputHumidAir.humidity(
+                (
+                    1 * first.humidity * (1 + second.humidity)
+                    + 2 * second.humidity * (1 + first.humidity)
+                )
+                / (1 * (1 + second.humidity) + 2 * (1 + first.humidity))
+            ),
         )