diff --git a/wolfcrypt/src/sp_c32.c b/wolfcrypt/src/sp_c32.c
index 38312e010..e5450b87d 100644
--- a/wolfcrypt/src/sp_c32.c
+++ b/wolfcrypt/src/sp_c32.c
@@ -54,7 +54,7 @@
 #if SP_WORD_SIZE == 32
 #if ((!defined(WC_NO_CACHE_RESISTANT) && \
       (defined(WOLFSSL_HAVE_SP_RSA) || defined(WOLFSSL_HAVE_SP_DH))) || \
-     defined(WOLFSSL_SP_SMALL)) && \
+     (defined(WOLFSSL_SP_SMALL) && !defined(WOLFSSL_SP_FAST_MODEXP))) && \
     (defined(WOLFSSL_HAVE_SP_ECC) || !defined(WOLFSSL_RSA_PUBLIC_ONLY))
 /* Mask for address to obfuscate which of the two address will be used. */
 static const size_t addr_mask[2] = { 0, (size_t)-1 };
@@ -1904,7 +1904,7 @@ static int sp_2048_mod_45(sp_digit* r, const sp_digit* a, const sp_digit* m)
 static int sp_2048_mod_exp_45(sp_digit* r, const sp_digit* a, const sp_digit* e,
     int bits, const sp_digit* m, int reduceA)
 {
-#ifdef WOLFSSL_SP_SMALL
+#if defined(WOLFSSL_SP_SMALL) && !defined(WOLFSSL_SP_FAST_MODEXP)
 #if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SP_NO_MALLOC)
     sp_digit* td = NULL;
 #else
@@ -2796,7 +2796,7 @@ static int sp_2048_mod_90(sp_digit* r, const sp_digit* a, const sp_digit* m)
 static int sp_2048_mod_exp_90(sp_digit* r, const sp_digit* a, const sp_digit* e,
     int bits, const sp_digit* m, int reduceA)
 {
-#ifdef WOLFSSL_SP_SMALL
+#if defined(WOLFSSL_SP_SMALL) && !defined(WOLFSSL_SP_FAST_MODEXP)
 #if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SP_NO_MALLOC)
     sp_digit* td = NULL;
 #else
@@ -5776,7 +5776,7 @@ static int sp_3072_mod_67(sp_digit* r, const sp_digit* a, const sp_digit* m)
 static int sp_3072_mod_exp_67(sp_digit* r, const sp_digit* a, const sp_digit* e,
     int bits, const sp_digit* m, int reduceA)
 {
-#ifdef WOLFSSL_SP_SMALL
+#if defined(WOLFSSL_SP_SMALL) && !defined(WOLFSSL_SP_FAST_MODEXP)
 #if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SP_NO_MALLOC)
     sp_digit* td = NULL;
 #else
@@ -6704,7 +6704,7 @@ static int sp_3072_mod_134(sp_digit* r, const sp_digit* a, const sp_digit* m)
 static int sp_3072_mod_exp_134(sp_digit* r, const sp_digit* a, const sp_digit* e,
     int bits, const sp_digit* m, int reduceA)
 {
-#ifdef WOLFSSL_SP_SMALL
+#if defined(WOLFSSL_SP_SMALL) && !defined(WOLFSSL_SP_FAST_MODEXP)
 #if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SP_NO_MALLOC)
     sp_digit* td = NULL;
 #else
@@ -9846,7 +9846,7 @@ static int sp_4096_mod_98(sp_digit* r, const sp_digit* a, const sp_digit* m)
 static int sp_4096_mod_exp_98(sp_digit* r, const sp_digit* a, const sp_digit* e,
     int bits, const sp_digit* m, int reduceA)
 {
-#ifdef WOLFSSL_SP_SMALL
+#if defined(WOLFSSL_SP_SMALL) && !defined(WOLFSSL_SP_FAST_MODEXP)
 #if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SP_NO_MALLOC)
     sp_digit* td = NULL;
 #else
@@ -10757,7 +10757,7 @@ static int sp_4096_mod_196(sp_digit* r, const sp_digit* a, const sp_digit* m)
 static int sp_4096_mod_exp_196(sp_digit* r, const sp_digit* a, const sp_digit* e,
     int bits, const sp_digit* m, int reduceA)
 {
-#ifdef WOLFSSL_SP_SMALL
+#if defined(WOLFSSL_SP_SMALL) && !defined(WOLFSSL_SP_FAST_MODEXP)
 #if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SP_NO_MALLOC)
     sp_digit* td = NULL;
 #else
diff --git a/wolfcrypt/src/sp_c64.c b/wolfcrypt/src/sp_c64.c
index 9f0594e78..a33bd2188 100644
--- a/wolfcrypt/src/sp_c64.c
+++ b/wolfcrypt/src/sp_c64.c
@@ -54,7 +54,7 @@
 #if SP_WORD_SIZE == 64
 #if ((!defined(WC_NO_CACHE_RESISTANT) && \
       (defined(WOLFSSL_HAVE_SP_RSA) || defined(WOLFSSL_HAVE_SP_DH))) || \
-     defined(WOLFSSL_SP_SMALL)) && \
+     (defined(WOLFSSL_SP_SMALL) && !defined(WOLFSSL_SP_FAST_MODEXP))) && \
     (defined(WOLFSSL_HAVE_SP_ECC) || !defined(WOLFSSL_RSA_PUBLIC_ONLY))
 /* Mask for address to obfuscate which of the two address will be used. */
 static const size_t addr_mask[2] = { 0, (size_t)-1 };
@@ -1531,7 +1531,7 @@ static int sp_2048_mod_18(sp_digit* r, const sp_digit* a, const sp_digit* m)
 static int sp_2048_mod_exp_18(sp_digit* r, const sp_digit* a, const sp_digit* e,
     int bits, const sp_digit* m, int reduceA)
 {
-#ifdef WOLFSSL_SP_SMALL
+#if defined(WOLFSSL_SP_SMALL) && !defined(WOLFSSL_SP_FAST_MODEXP)
 #if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SP_NO_MALLOC)
     sp_digit* td = NULL;
 #else
@@ -2418,7 +2418,7 @@ static int sp_2048_mod_36(sp_digit* r, const sp_digit* a, const sp_digit* m)
 static int sp_2048_mod_exp_36(sp_digit* r, const sp_digit* a, const sp_digit* e,
     int bits, const sp_digit* m, int reduceA)
 {
-#ifdef WOLFSSL_SP_SMALL
+#if defined(WOLFSSL_SP_SMALL) && !defined(WOLFSSL_SP_FAST_MODEXP)
 #if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SP_NO_MALLOC)
     sp_digit* td = NULL;
 #else
@@ -5765,7 +5765,7 @@ static int sp_3072_mod_27(sp_digit* r, const sp_digit* a, const sp_digit* m)
 static int sp_3072_mod_exp_27(sp_digit* r, const sp_digit* a, const sp_digit* e,
     int bits, const sp_digit* m, int reduceA)
 {
-#ifdef WOLFSSL_SP_SMALL
+#if defined(WOLFSSL_SP_SMALL) && !defined(WOLFSSL_SP_FAST_MODEXP)
 #if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SP_NO_MALLOC)
     sp_digit* td = NULL;
 #else
@@ -6659,7 +6659,7 @@ static int sp_3072_mod_54(sp_digit* r, const sp_digit* a, const sp_digit* m)
 static int sp_3072_mod_exp_54(sp_digit* r, const sp_digit* a, const sp_digit* e,
     int bits, const sp_digit* m, int reduceA)
 {
-#ifdef WOLFSSL_SP_SMALL
+#if defined(WOLFSSL_SP_SMALL) && !defined(WOLFSSL_SP_FAST_MODEXP)
 #if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SP_NO_MALLOC)
     sp_digit* td = NULL;
 #else
@@ -10121,7 +10121,7 @@ static int sp_4096_mod_39(sp_digit* r, const sp_digit* a, const sp_digit* m)
 static int sp_4096_mod_exp_39(sp_digit* r, const sp_digit* a, const sp_digit* e,
     int bits, const sp_digit* m, int reduceA)
 {
-#ifdef WOLFSSL_SP_SMALL
+#if defined(WOLFSSL_SP_SMALL) && !defined(WOLFSSL_SP_FAST_MODEXP)
 #if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SP_NO_MALLOC)
     sp_digit* td = NULL;
 #else
@@ -11074,7 +11074,7 @@ static int sp_4096_mod_78(sp_digit* r, const sp_digit* a, const sp_digit* m)
 static int sp_4096_mod_exp_78(sp_digit* r, const sp_digit* a, const sp_digit* e,
     int bits, const sp_digit* m, int reduceA)
 {
-#ifdef WOLFSSL_SP_SMALL
+#if defined(WOLFSSL_SP_SMALL) && !defined(WOLFSSL_SP_FAST_MODEXP)
 #if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_SP_NO_MALLOC)
     sp_digit* td = NULL;
 #else
diff --git a/wolfcrypt/src/sp_int.c b/wolfcrypt/src/sp_int.c
index 6cee7fb50..067784c77 100644
--- a/wolfcrypt/src/sp_int.c
+++ b/wolfcrypt/src/sp_int.c
@@ -82,6 +82,7 @@ This library provides single precision (SP) integer math functions.
  *                              pointer is not allowed.
  * WOLFSSL_SP_NO_DYN_STACK      Disable use of dynamic stack items.
  *                              Used with small code size and not small stack.
+ * WOLFSSL_SP_FAST_MODEXP       Allow fast mod_exp with small C code
  */
 
 #if defined(WOLFSSL_SP_MATH) || defined(WOLFSSL_SP_MATH_ALL)