diff --git a/src/xmalloc.c b/src/xmalloc.c
index 135a5c7e..a4acddc7 100644
--- a/src/xmalloc.c
+++ b/src/xmalloc.c
@@ -79,12 +79,12 @@ struct xmalloc_slot {
         #define MP_CURVE_SPECS_SIZE (112)
         #ifdef WOLFSSL_SP_ARM_CORTEX_M_ASM
             #define MP_POINT_SIZE (292)
-            #define MP_DIGITS_BUFFER_SIZE_0 (MP_DIGIT_SIZE * 16 * 12)
+            #define MP_DIGITS_BUFFER_SIZE_0 (MP_DIGIT_SIZE * 18 * 12)
             #define MP_DIGITS_BUFFER_SIZE_1 (MP_DIGIT_SIZE * 2 * 12 * 6)
             #define MP_MONTGOMERY_SIZE (sizeof(int64_t) * 12)
         #else
             #define MP_POINT_SIZE (364)
-            #define MP_DIGITS_BUFFER_SIZE_0 (MP_DIGIT_SIZE * 16 * 15)
+            #define MP_DIGITS_BUFFER_SIZE_0 (MP_DIGIT_SIZE * 18 * 15)
             #define MP_DIGITS_BUFFER_SIZE_1 (MP_DIGIT_SIZE * (4 * 15 + 3))
             #define MP_DIGITS_BUFFER_SIZE_2 (MP_DIGIT_SIZE * (2 * 15 * 6))
             #define MP_MONTGOMERY_SIZE (sizeof(int64_t) * 2 * 12)