diff --git a/wolfcrypt/src/random.c b/wolfcrypt/src/random.c
index e8070a355..bd8a2142a 100644
--- a/wolfcrypt/src/random.c
+++ b/wolfcrypt/src/random.c
@@ -917,6 +917,9 @@ int wc_RNG_GenerateBlock(WC_RNG* rng, byte* output, word32 sz)
     if (rng == NULL || output == NULL)
         return BAD_FUNC_ARG;
 
+    if (sz == 0)
+        return 0; 
+
 #ifdef WOLF_CRYPTO_CB
     if (rng->devId != INVALID_DEVID) {
         ret = wc_CryptoCb_RandomBlock(rng, output, sz);
diff --git a/wolfcrypt/src/sp_int.c b/wolfcrypt/src/sp_int.c
index af1c9c244..fc093e8e7 100644
--- a/wolfcrypt/src/sp_int.c
+++ b/wolfcrypt/src/sp_int.c
@@ -9240,7 +9240,7 @@ int sp_div_2d(sp_int* a, int e, sp_int* r, sp_int* rem)
                 rem->used = (e + SP_WORD_SIZE - 1) >> SP_WORD_SHIFT;
                 e &= SP_WORD_MASK;
                 if (e > 0) {
-                    rem->dp[rem->used - 1] &= (1 << e) - 1;
+                    rem->dp[rem->used - 1] &= ((sp_int_digit)1 << e) - 1;
                 }
                 sp_clamp(rem);
             }
@@ -12979,10 +12979,13 @@ int sp_rand_prime(sp_int* r, int len, WC_RNG* rng, void* heap)
 
     (void)heap;
 
-    if ((r == NULL) || (rng == NULL)) {
+    if ((r == NULL) || (rng == NULL) || len < 0 ) {
         err = MP_VAL;
     }
 
+    if (len == 0)
+        return MP_OKAY;
+
     if (err == MP_OKAY) {
         /* get type */
         if (len < 0) {