diff --git a/GenTunic/gen_util.py b/GenTunic/gen_util.py
index c63b5c2..56c4d7f 100644
--- a/GenTunic/gen_util.py
+++ b/GenTunic/gen_util.py
@@ -102,8 +102,11 @@ def mutation(population, MUTATION_RATE, GEN_SIZE):
 
     for individual_index in mutation_indecies:
         bit_index = np.random.randint(0, GEN_SIZE)
-        bit_to_mutate = population[individual_index]["population"][bit_index]
-        mutated_grey = bit_to_grey(bit_to_mutate) ^ 1
-        population[individual_index]["population"][bit_index] = grey_to_bit(mutated_grey)
+        bit_to_mutate = population[individual_index]["population"]
+
+        grey_to_mutate = bit_to_grey(bit_to_mutate)
+        grey_to_mutate[bit_index] ^= 1
+
+        population[individual_index]["population"] = grey_to_bit(grey_to_mutate)
 
     return population
\ No newline at end of file