diff --git a/aes.c b/aes.c
index aa45fbf..3025fa4 100644
--- a/aes.c
+++ b/aes.c
@@ -124,7 +124,7 @@ static uint8_t getSBoxValue(uint8_t num)
 // This function produces Nb(Nr+1) round keys. The round keys are used in each round to decrypt the states. 
 static void KeyExpansion()
 {
-  uint8_t i, j, k;
+  uint32_t i, j, k;
   uint8_t tempa[4]; // used for the column/row operations
   
   // The first round key is the key itself.