diff --git a/channels/smartcard/client/smartcard_pack.c b/channels/smartcard/client/smartcard_pack.c
index f9f9f6c9f..4eac717b5 100644
--- a/channels/smartcard/client/smartcard_pack.c
+++ b/channels/smartcard/client/smartcard_pack.c
@@ -146,7 +146,10 @@ UINT32 smartcard_pack_write_size_align(SMARTCARD_DEVICE* smartcard, wStream* s,
 	pad = size - pad;
 
 	if (pad)
+	{
+		Stream_EnsureRemainingCapacity(s, pad);
 		Stream_Zero(s, pad);
+	}
 
 	return pad;
 }
@@ -2423,9 +2426,11 @@ UINT32 smartcard_pack_transmit_return(SMARTCARD_DEVICE* smartcard, wStream* s, T
 		Stream_Write_UINT32(s, pbExtraBytesNdrPtr); /* pbExtraBytesNdrPtr (4 bytes) */
 
 		if (pbExtraBytesNdrPtr)
+		{
+			Stream_Write_UINT32(s, cbExtraBytes); /* Length (4 bytes) */
 			Stream_Write(s, pbExtraBytes, cbExtraBytes);
-
-		smartcard_pack_write_size_align(smartcard, s, cbExtraBytes, 4);
+			smartcard_pack_write_size_align(smartcard, s, cbExtraBytes, 4);
+		}
 	}
 
 	if (pbRecvBufferNdrPtr)
diff --git a/winpr/libwinpr/smartcard/smartcard_pcsc.c b/winpr/libwinpr/smartcard/smartcard_pcsc.c
index cc48489ee..7e154ac45 100644
--- a/winpr/libwinpr/smartcard/smartcard_pcsc.c
+++ b/winpr/libwinpr/smartcard/smartcard_pcsc.c
@@ -2178,7 +2178,7 @@ WINSCARDAPI LONG WINAPI PCSC_SCardTransmit(SCARDHANDLE hCard,
 	}
 
 	status = (LONG) g_PCSC.pfnSCardTransmit(hCard, pcsc_pioSendPci, pbSendBuffer,
-											pcsc_cbSendLength, pcsc_pioRecvPci, pbRecvBuffer, &pcsc_cbRecvLength);
+				pcsc_cbSendLength, pcsc_pioRecvPci, pbRecvBuffer, &pcsc_cbRecvLength);
 	status = PCSC_MapErrorCodeToWinSCard(status);
 	*pcbRecvLength = (DWORD) pcsc_cbRecvLength;
 
@@ -2186,7 +2186,13 @@ WINSCARDAPI LONG WINAPI PCSC_SCardTransmit(SCARDHANDLE hCard,
 		free(pcsc_pioSendPci); /* pcsc_pioSendPci is dynamically allocated only when pioSendPci is non null */
 
 	if (pioRecvPci)
+	{
+		cbExtraBytes = pioRecvPci->cbPciLength - sizeof(SCARD_IO_REQUEST);
+		pbExtraBytes = &((BYTE*) pioRecvPci)[sizeof(SCARD_IO_REQUEST)];
+		pcsc_pbExtraBytes = &((BYTE*) pcsc_pioRecvPci)[sizeof(PCSC_SCARD_IO_REQUEST)];
+		CopyMemory(pbExtraBytes, pcsc_pbExtraBytes, cbExtraBytes); /* copy extra bytes */
 		free(pcsc_pioRecvPci); /* pcsc_pioRecvPci is dynamically allocated only when pioRecvPci is non null */
+	}
 
 	return status;
 }