diff --git a/speck.h b/speck.h
index 6571074e..c027feb0 100644
--- a/speck.h
+++ b/speck.h
@@ -16,7 +16,7 @@
 #include "seckey.h"
 #include "secblock.h"
 
-#if CRYPTOPP_BOOL_X64 || CRYPTOPP_BOOL_X32 || CRYPTOPP_BOOL_X86 || CRYPTOPP_BOOL_ARM32 || CRYPTOPP_BOOL_ARM64
+#if CRYPTOPP_BOOL_X64 || CRYPTOPP_BOOL_X32 || CRYPTOPP_BOOL_X86
 # define CRYPTOPP_SPECK64_ADVANCED_PROCESS_BLOCKS 1
 #endif