diff --git a/src/scsi/scsi_disk.c b/src/scsi/scsi_disk.c
index d36d152..8422941 100644
--- a/src/scsi/scsi_disk.c
+++ b/src/scsi/scsi_disk.c
@@ -860,13 +860,13 @@ scsi_hd_command(uint8_t id, uint8_t *cdb)
 {
     /* uint8_t *hdbufferb = (uint8_t *) shdc[id].buffer; */
     uint8_t *hdbufferb = SCSIDevices[hdd[id].scsi_id][hdd[id].scsi_lun].CmdBuffer;
-    uint32_t len;
+    int32_t len;
     int pos=0;
     int max_len;
-    unsigned idx = 0;
+    int idx = 0;
     unsigned size_idx;
     unsigned preamble_len;
-    uint32_t alloc_length;
+    int32_t alloc_length;
     char device_identify[9] = {
 	'E','M','U','_','H','D','0','0',0 };
     char device_identify_ex[15] = {
@@ -1450,7 +1450,7 @@ void
 scsi_hd_phase_data_out(uint8_t id)
 {
     uint8_t *hdbufferb = SCSIDevices[hdd[id].scsi_id][hdd[id].scsi_lun].CmdBuffer;
-    int i;
+    uint32_t i;
     int32_t *BufLen = &SCSIDevices[hdd[id].scsi_id][hdd[id].scsi_lun].BufferLength;
     uint32_t last_sector = hdd_image_get_last_sector(id);
     uint32_t last_to_write = 0;
diff --git a/src/scsi/scsi_ncr53c810.c b/src/scsi/scsi_ncr53c810.c
index 8b55ead..7666d4c 100644
--- a/src/scsi/scsi_ncr53c810.c
+++ b/src/scsi/scsi_ncr53c810.c
@@ -411,7 +411,7 @@ ncr53c810_soft_reset(ncr53c810_t *dev)
 static void
 ncr53c810_read(ncr53c810_t *dev, uint32_t addr, uint8_t *buf, uint32_t len)
 {
-	int i = 0;
+	uint32_t i = 0;
 
 	ncr53c810_log("ncr53c810_read(): %08X-%08X, length %i\n", addr, (addr + len - 1), len);
 
@@ -429,7 +429,7 @@ ncr53c810_read(ncr53c810_t *dev, uint32_t addr, uint8_t *buf, uint32_t len)
 static void
 ncr53c810_write(ncr53c810_t *dev, uint32_t addr, uint8_t *buf, uint32_t len)
 {
-	int i = 0;
+	uint32_t i = 0;
 
 	ncr53c810_log("ncr53c810_write(): %08X-%08X, length %i\n", addr, (addr + len - 1), len);
 
@@ -604,7 +604,8 @@ ncr53c810_command_complete(void *priv, uint32_t status)
 static void
 ncr53c810_do_dma(ncr53c810_t *dev, int out, uint8_t id)
 {
-    uint32_t addr, count, tdbc;
+    uint32_t addr, tdbc;
+    int32_t count;
 
     scsi_device_t *sd;
 
@@ -767,7 +768,7 @@ ncr53c810_do_status(ncr53c810_t *dev)
 static void
 ncr53c810_do_msgin(ncr53c810_t *dev)
 {
-    int len;
+    uint32_t len;
     ncr53c810_log("Message in len=%d/%d\n", dev->dbc, dev->msg_len);
     dev->sfbr = dev->msg[0];
     len = dev->msg_len;
diff --git a/src/scsi/scsi_x54x.c b/src/scsi/scsi_x54x.c
index 8ef2696..ff7f9ed 100644
--- a/src/scsi/scsi_x54x.c
+++ b/src/scsi/scsi_x54x.c
@@ -739,7 +739,7 @@ x54x_get_length(Req_t *req, int Is24bit)
     uint32_t SGEntryLength = (Is24bit ? sizeof(SGE) : sizeof(SGE32));
     SGE32 SGBuffer;
     uint32_t DataToTransfer = 0;
-    int i = 0;
+    uint32_t i = 0;
 
     if (Is24bit) {
 	DataPointer = ADDR_TO_U32(req->CmdBlock.old.DataPointer);
@@ -812,8 +812,8 @@ x54x_buf_dma_transfer(Req_t *req, int Is24bit, int TransferLength, int dir)
     uint32_t DataPointer, DataLength;
     uint32_t SGEntryLength = (Is24bit ? sizeof(SGE) : sizeof(SGE32));
     uint32_t Address;
-    int i = 0;
-    int32_t BufLen = SCSIDevices[req->TargetID][req->LUN].BufferLength;
+    uint32_t i = 0;
+    uint32_t BufLen = SCSIDevices[req->TargetID][req->LUN].BufferLength;
     uint8_t read_from_host = (dir && ((req->CmdBlock.common.ControlByte == CCB_DATA_XFER_OUT) || (req->CmdBlock.common.ControlByte == 0x00)));
     uint8_t write_to_host = (!dir && ((req->CmdBlock.common.ControlByte == CCB_DATA_XFER_IN) || (req->CmdBlock.common.ControlByte == 0x00)));
     int sg_pos = 0;