diff --git a/wolfcrypt/src/ascon.c b/wolfcrypt/src/ascon.c
index 4da892c53..775614a7b 100644
--- a/wolfcrypt/src/ascon.c
+++ b/wolfcrypt/src/ascon.c
@@ -48,6 +48,10 @@
  * - Add support for big-endian systems
  * - Add support for 32-bit and smaller systems */
 
+#ifndef WORD64_AVAILABLE
+    #error "Ascon implementation requires a 64-bit word"
+#endif
+
 /* Data block size in bytes */
 #define ASCON_HASH256_RATE                              8
 #define ASCON_HASH256_ROUNDS                           12
diff --git a/wolfssl/wolfcrypt/ascon.h b/wolfssl/wolfcrypt/ascon.h
index 3e95d521f..52cb889f7 100644
--- a/wolfssl/wolfcrypt/ascon.h
+++ b/wolfssl/wolfcrypt/ascon.h
@@ -37,7 +37,9 @@ extern "C" {
 #define ASCON_AEAD128_TAG_SZ                           16
 
 typedef union AsconState {
+#ifdef WORD64_AVAILABLE
     word64 s64[5];
+#endif
     word32 s32[10];
     word16 s16[20];
     byte    s8[40];
@@ -56,7 +58,9 @@ enum {
 
 typedef struct wc_AsconAEAD128 {
     /* needed throughout both encrypt and decrypt */
+#ifdef WORD64_AVAILABLE
     word64 key[ASCON_AEAD128_KEY_SZ/sizeof(word64)];
+#endif
     AsconState state;
     byte lastBlkSz;
     byte KeySet:1;   /* has the key been processed */