diff --git a/aes.h b/aes.h
index b29b668..143b7d6 100644
--- a/aes.h
+++ b/aes.h
@@ -24,9 +24,13 @@
 #endif
 
 
+#ifndef AES128
+#ifndef AES192
+#ifndef AES256
 #define AES128 1
-//#define AES192 1
-//#define AES256 1
+#endif
+#endif
+#endif
 
 #define AES_BLOCKLEN 16 // Block length in bytes - AES is 128b block only