diff --git a/src/bio.c b/src/bio.c
index beb0acfe6..1a19f586f 100644
--- a/src/bio.c
+++ b/src/bio.c
@@ -328,30 +328,41 @@ int wolfSSL_BIO_write(WOLFSSL_BIO* bio, const void* data, int len)
     while (bio != NULL && ret >= 0) {
         /* check for formating */
         if (bio && bio->type == WOLFSSL_BIO_BASE64) {
-
 #if defined(WOLFSSL_BASE64_ENCODE)
+            word32 sz = 0;
+
             if (bio->flags & WOLFSSL_BIO_FLAG_BASE64_NO_NL) {
                 if (Base64_Encode_NoNl((const byte*)data, len, NULL,
-                            &frmtSz) != LENGTH_ONLY_E) {
+                            &sz) != LENGTH_ONLY_E) {
                     WOLFSSL_MSG("Error with base 64 get length");
                     ret = SSL_FATAL_ERROR;
                 }
             }
             else {
-                if (Base64_Encode((const byte*)data, len, NULL, &frmtSz) !=
+                if (Base64_Encode((const byte*)data, len, NULL, &sz) !=
                     LENGTH_ONLY_E) {
                     WOLFSSL_MSG("Error with base 64 get length");
                     ret = SSL_FATAL_ERROR;
                 }
             }
 
-            if (frmt == NULL && frmtSz > 0 && ret != SSL_FATAL_ERROR) {
-                frmt = (void*)XMALLOC(frmtSz, bio->heap,
+            if (frmt == NULL && sz > 0 && ret != SSL_FATAL_ERROR) {
+                frmt = (void*)XMALLOC(sz, front->heap,
                         DYNAMIC_TYPE_TMP_BUFFER);
                 if (frmt == NULL) {
                     WOLFSSL_MSG("Memory error");
                     ret = SSL_FATAL_ERROR;
                 }
+                frmtSz = sz;
+            }
+            else if (sz > frmtSz) {
+                frmt = (void*)XREALLOC(frmt, sz, front->heap,
+                        DYNAMIC_TYPE_TMP_BUFFER);
+                if (frmt == NULL) {
+                    WOLFSSL_MSG("Memory error");
+                    ret = SSL_FATAL_ERROR;
+                }
+                frmtSz = sz;
             }
 #endif /* defined(WOLFSSL_BASE64_ENCODE) */
 
@@ -394,7 +405,7 @@ int wolfSSL_BIO_write(WOLFSSL_BIO* bio, const void* data, int len)
     }
 
     if (frmt != NULL) {
-        XFREE(frmt, bio->heap, DYNAMIC_TYPE_TMP_BUFFER);
+        XFREE(frmt, front->heap, DYNAMIC_TYPE_TMP_BUFFER);
     }
 
     return ret;
diff --git a/tests/api.c b/tests/api.c
index f7c245421..5f1784cbd 100644
--- a/tests/api.c
+++ b/tests/api.c
@@ -15579,6 +15579,21 @@ static void test_wolfSSL_BIO_write(void)
     AssertIntEQ(XMEMCMP(out, expected, sz), 0);
 
     BIO_free_all(bio); /* frees bio64 also */
+
+    /* test with more than one bio64 in list */
+    AssertNotNull(bio64 = BIO_new(BIO_f_base64()));
+    AssertNotNull(bio   = BIO_push(bio64, BIO_new(BIO_f_base64())));
+    AssertNotNull(bio   = BIO_push(bio, BIO_new(BIO_s_mem())));
+
+    /* now should convert to base64(x2) when stored and then decode with read */
+    AssertIntEQ(BIO_write(bio, msg, sizeof(msg)), 25);
+    BIO_flush(bio);
+    sz = sizeof(out);
+    XMEMSET(out, 0, sz);
+    AssertIntEQ((sz = BIO_read(bio, out, sz)), 16);
+    AssertIntEQ(XMEMCMP(out, msg, sz), 0);
+    BIO_free_all(bio); /* frees bio64s also */
+
     printf(resultFmt, passed);
     #endif
 }