diff --git a/libztex.c b/libztex.c
index 636c12c4..95c83f74 100644
--- a/libztex.c
+++ b/libztex.c
@@ -607,11 +607,19 @@ int libztex_scanDevices(struct libztex_dev_list*** devs_p)
 
 int libztex_sendHashData(struct libztex_device *ztex, unsigned char *sendbuf)
 {
-	int cnt;
+	int cnt, ret;
 
 	if (ztex == NULL || ztex->hndl == NULL)
 		return 0;
-	cnt = libusb_control_transfer(ztex->hndl, 0x40, 0x80, 0, 0, sendbuf, 44, 1000);
+	ret = 44;
+	while (ret > 0) {
+		cnt = libusb_control_transfer(ztex->hndl, 0x40, 0x80, 0, 0, sendbuf, ret, 1000);
+		if (cnt >= 0)
+			ret -= cnt;
+		else
+			if (cnt != LIBUSB_ERROR_TIMEOUT)
+				break;
+	}
 	if (unlikely(cnt < 0))
 		applog(LOG_ERR, "%s: Failed sendHashData with err %d", ztex->repr, cnt);
 	
@@ -621,7 +629,7 @@ int libztex_sendHashData(struct libztex_device *ztex, unsigned char *sendbuf)
 int libztex_readHashData(struct libztex_device *ztex, struct libztex_hash_data nonces[]) {
 	int bufsize = 12 + ztex->extraSolutions * 4;
 	unsigned char *rbuf;
-	int cnt, i, j;
+	int cnt, i, j, ret;
 
 	if (ztex->hndl == NULL)
 		return 0;
@@ -631,7 +639,16 @@ int libztex_readHashData(struct libztex_device *ztex, struct libztex_hash_data n
 		applog(LOG_ERR, "%s: Failed to allocate memory for reading nonces", ztex->repr);
 		return 0;
 	}
-	cnt = libusb_control_transfer(ztex->hndl, 0xc0, 0x81, 0, 0, rbuf, bufsize * ztex->numNonces, 1000);
+	ret = bufsize * ztex->numNonces;
+	while (ret > 0) {
+		cnt = libusb_control_transfer(ztex->hndl, 0xc0, 0x81, 0, 0, rbuf, ret, 1000);
+		if (cnt >= 0)
+			ret -= cnt;
+		else
+			if (cnt != LIBUSB_ERROR_TIMEOUT)
+				break;
+	}
+
 	if (unlikely(cnt < 0)) {
 		applog(LOG_ERR, "%s: Failed readHashData with err %d", ztex->repr, cnt);
 		free(rbuf);