diff --git a/src/internal.c b/src/internal.c
index 2d83cdbbb9..4d4d28353b 100644
--- a/src/internal.c
+++ b/src/internal.c
@@ -9784,11 +9784,6 @@ static int wolfSSLReceive(WOLFSSL* ssl, byte* buf, word32 sz)
 void ShrinkOutputBuffer(WOLFSSL* ssl)
 {
     WOLFSSL_MSG("Shrinking output buffer");
-    if (IsEncryptionOn(ssl, 0)) {
-        ForceZero(ssl->buffers.outputBuffer.buffer -
-            ssl->buffers.outputBuffer.offset,
-            ssl->buffers.outputBuffer.bufferSize);
-    }
     XFREE(ssl->buffers.outputBuffer.buffer - ssl->buffers.outputBuffer.offset,
           ssl->heap, DYNAMIC_TYPE_OUT_BUFFER);
     ssl->buffers.outputBuffer.buffer = ssl->buffers.outputBuffer.staticBuffer;
@@ -9819,11 +9814,9 @@ void ShrinkInputBuffer(WOLFSSL* ssl, int forcedFree)
                usedLength);
     }
 
-    if (IsEncryptionOn(ssl, 1) || forcedFree) {
-        ForceZero(ssl->buffers.inputBuffer.buffer -
-            ssl->buffers.inputBuffer.offset,
-            ssl->buffers.inputBuffer.bufferSize);
-    }
+    ForceZero(ssl->buffers.inputBuffer.buffer -
+        ssl->buffers.inputBuffer.offset,
+        ssl->buffers.inputBuffer.bufferSize);
     XFREE(ssl->buffers.inputBuffer.buffer - ssl->buffers.inputBuffer.offset,
           ssl->heap, DYNAMIC_TYPE_IN_BUFFER);
     ssl->buffers.inputBuffer.buffer = ssl->buffers.inputBuffer.staticBuffer;
@@ -9968,11 +9961,6 @@ static WC_INLINE int GrowOutputBuffer(WOLFSSL* ssl, int size)
                ssl->buffers.outputBuffer.length);
 
     if (ssl->buffers.outputBuffer.dynamicFlag) {
-        if (IsEncryptionOn(ssl, 0)) {
-            ForceZero(ssl->buffers.outputBuffer.buffer -
-                ssl->buffers.outputBuffer.offset,
-                ssl->buffers.outputBuffer.bufferSize);
-        }
         XFREE(ssl->buffers.outputBuffer.buffer -
               ssl->buffers.outputBuffer.offset, ssl->heap,
               DYNAMIC_TYPE_OUT_BUFFER);
@@ -20819,8 +20807,17 @@ int BuildMessage(WOLFSSL* ssl, byte* output, int outSz, const byte* input,
     #endif
             }
 
-            if (ret != 0)
+            if (ret != 0) {
+            #ifdef WOLFSSL_ASYNC_CRYPT
+                if (ret != WC_PENDING_E)
+            #endif
+                {
+                    /* Zeroize plaintext. */
+                    ForceZero(output + args->headerSz,
+                        (word16)(args->size - args->digestSz));
+                }
                 goto exit_buildmsg;
+            }
             ssl->options.buildMsgState = BUILD_MSG_ENCRYPTED_VERIFY_MAC;
         }
         FALL_THROUGH;
diff --git a/src/tls13.c b/src/tls13.c
index 7cbe43cc5d..4a6bcfd90d 100644
--- a/src/tls13.c
+++ b/src/tls13.c
@@ -3008,6 +3008,15 @@ int BuildTls13Message(WOLFSSL* ssl, byte* output, int outSz, const byte* input,
                 output += args->headerSz;
                 ret = EncryptTls13(ssl, output, output, args->size, aad,
                                    (word16)args->headerSz, asyncOkay);
+                if (ret != 0) {
+                #ifdef WOLFSSL_ASYNC_CRYPT
+                    if (ret != WC_PENDING_E)
+                #endif
+                    {
+                        /* Zeroize plaintext. */
+                        ForceZero(output, args->size);
+                    }
+                }
 #ifdef WOLFSSL_DTLS13
                 if (ret == 0 && ssl->options.dtls) {
                     /* AAD points to the header. Reuse the variable  */
diff --git a/wolfcrypt/src/dh.c b/wolfcrypt/src/dh.c
index 900729e374..bf54ecc580 100644
--- a/wolfcrypt/src/dh.c
+++ b/wolfcrypt/src/dh.c
@@ -1161,6 +1161,8 @@ static int GeneratePrivateDh186(DhKey* key, WC_RNG* rng, byte* priv,
     ForceZero(cBuf, cSz);
 #if defined(WOLFSSL_SMALL_STACK) && !defined(WOLFSSL_NO_MALLOC)
     XFREE(cBuf, key->heap, DYNAMIC_TYPE_TMP_BUFFER);
+#elif defined(WOLFSSL_CHECK_MEM_ZERO)
+    wc_MemZero_Check(cBuf, cSz);
 #endif
 
     /* tmpQ: M = min(2^N,q) - 1 */
diff --git a/wolfcrypt/src/sp_int.c b/wolfcrypt/src/sp_int.c
index 0130cf3e28..8a1d125fab 100644
--- a/wolfcrypt/src/sp_int.c
+++ b/wolfcrypt/src/sp_int.c
@@ -4687,7 +4687,7 @@ void sp_forcezero(sp_int* a)
 {
     if (a != NULL) {
         /* Ensure all data zeroized - data not zeroed when used decreases. */
-        ForceZero(a->dp, a->used * sizeof(sp_int_digit));
+        ForceZero(a->dp, a->size * sizeof(sp_int_digit));
         _sp_zero(a);
     #ifdef HAVE_WOLF_BIGINT
         wc_bigint_zero(&a->raw);