diff --git a/armsrc/optimized_ikeys.h b/armsrc/optimized_ikeys.h
index 91fa406ad..0915482e3 100644
--- a/armsrc/optimized_ikeys.h
+++ b/armsrc/optimized_ikeys.h
@@ -59,7 +59,7 @@ void hash0(uint64_t c, uint8_t k[8]);
  * @param div_key
  */
 
-void diversifyKey(uint8_t csn[8], uint8_t key[8], uint8_t div_key[8]);
+void diversifyKey(uint8_t *csn, *uint8_t key, uint8_t *div_key);
 /**
  * @brief Permutes a key from standard NIST format to Iclass specific format
  * @param key