diff --git a/firehose.c b/firehose.c
index e6e8953..f3fd153 100644
--- a/firehose.c
+++ b/firehose.c
@@ -341,7 +341,7 @@ static int firehose_try_configure(struct qdl_device *qdl, bool skip_storage_init
 	size_t size = 0;
 	void *buf;
 	int ret;
-	int i;
+	unsigned int i;
 
 	ret = firehose_send_configure(qdl, qdl->max_payload_size, skip_storage_init,
 				      storage, &size);
@@ -454,6 +454,7 @@ static int firehose_program(struct qdl_device *qdl, struct program *program, int
 	int left;
 	int ret;
 	int n;
+	size_t i;
 	uint32_t fill_value;
 
 	/*
@@ -526,8 +527,8 @@ static int firehose_program(struct qdl_device *qdl, struct program *program, int
 			break;
 		case CHUNK_TYPE_FILL:
 			fill_value = program->sparse_fill_value;
-			for (n = 0; n < qdl->max_payload_size; n += sizeof(fill_value))
-				memcpy(buf + n, &fill_value, sizeof(fill_value));
+			for (i = 0; i < qdl->max_payload_size; i += sizeof(fill_value))
+				memcpy(buf + i, &fill_value, sizeof(fill_value));
 			break;
 		default:
 			ux_err("[SPARSE] invalid chunk type\n");
@@ -555,7 +556,7 @@ static int firehose_program(struct qdl_device *qdl, struct program *program, int
 				goto out;
 			}
 
-			if (n < qdl->max_payload_size)
+			if ((size_t)n < qdl->max_payload_size)
 				memset(buf + n, 0, qdl->max_payload_size - n);
 		}
 
@@ -587,7 +588,7 @@ static int firehose_program(struct qdl_device *qdl, struct program *program, int
 			goto out;
 		}
 
-		if (n != chunk_size * sector_size) {
+		if ((size_t)n != chunk_size * sector_size) {
 			ux_err("USB write truncated\n");
 			ret = -1;
 			goto out;
@@ -686,12 +687,12 @@ static int firehose_issue_read(struct qdl_device *qdl, struct read_op *read_op,
 			continue;
 		} else if (expect_empty) {
 			err(1, "expected empty transfer but received non-empty transfer during read");
-		} else if (n != chunk_size * sector_size) {
+		} else if ((size_t)n != chunk_size * sector_size) {
 			err(1, "failed to read full sector");
 		}
 
 		if (out_buf) {
-			if (n > out_len - out_offset)
+			if ((size_t)n > out_len - out_offset)
 				n = out_len - out_offset;
 
 			memcpy(out_buf + out_offset, buf, n);
@@ -699,7 +700,7 @@ static int firehose_issue_read(struct qdl_device *qdl, struct read_op *read_op,
 		} else {
 			n = write(fd, buf, n);
 
-			if (n != chunk_size * sector_size) {
+			if (n < 0 || (size_t)n != chunk_size * sector_size) {
 				err(1, "failed to write");
 			}
 		}
diff --git a/gpt.c b/gpt.c
index 188e8e3..cec962d 100644
--- a/gpt.c
+++ b/gpt.c
@@ -145,7 +145,7 @@ static int gpt_load_table_from_partition(struct qdl_device *qdl, unsigned int ph
 	uint16_t name_utf16le[36];
 	char name[36 * 4];
 	int ret;
-	int i;
+	unsigned int i;
 
 	memset(&op, 0, sizeof(op));
 
diff --git a/sahara.c b/sahara.c
index 501316b..f3bda42 100644
--- a/sahara.c
+++ b/sahara.c
@@ -180,7 +180,7 @@ static void sahara_read(struct qdl_device *qdl, struct sahara_pkt *pkt,
 	}
 
 	ret = qdl_write(qdl, image->ptr + offset, len, SAHARA_CMD_TIMEOUT_MS);
-	if (ret != len)
+	if (ret < 0 || ((size_t)ret != len))
 		err(1, "failed to write %zu bytes to sahara", len);
 }
 
@@ -220,7 +220,7 @@ static void sahara_read64(struct qdl_device *qdl, struct sahara_pkt *pkt,
 	}
 
 	ret = qdl_write(qdl, image->ptr + offset, len, SAHARA_CMD_TIMEOUT_MS);
-	if (ret != len)
+	if (ret < 0 || ((size_t)ret != len))
 		err(1, "failed to write %zu bytes to sahara", len);
 }
 
@@ -302,7 +302,7 @@ static ssize_t sahara_debug64_one(struct qdl_device *qdl,
 				goto out;
 			}
 
-			while (buf_offset < n) {
+			while (buf_offset < (size_t)n) {
 				written = write(fd, buf + buf_offset, n - buf_offset);
 				if (written <= 0) {
 					warn("failed to write ramdump chunk to \"%s\"", region.filename);
@@ -373,7 +373,7 @@ static void sahara_debug64(struct qdl_device *qdl, struct sahara_pkt *pkt,
 	struct sahara_debug_region64 *table;
 	struct sahara_pkt read_req;
 	ssize_t n;
-	int i;
+	size_t i;
 
 	assert(pkt->length == SAHARA_MEM_DEBUG64_LENGTH);
 
@@ -455,7 +455,7 @@ int sahara_run(struct qdl_device *qdl, const struct sahara_image *images,
 		}
 
 		pkt = (struct sahara_pkt *)buf;
-		if (n != pkt->length) {
+		if ((uint32_t)n != pkt->length) {
 			ux_err("request length not matching received request\n");
 			return -EINVAL;
 		}
diff --git a/util.c b/util.c
index 36b0bcc..31da16b 100644
--- a/util.c
+++ b/util.c
@@ -39,8 +39,8 @@ void print_hex_dump(const char *prefix, const void *buf, size_t len)
 	uint8_t ch;
 	char line[16 * 3 + 16 + 1];
 	int li;
-	int i;
-	int j;
+	unsigned int i;
+	unsigned int j;
 
 	for (i = 0; i < len; i += 16) {
 		linelen = MIN(16, len - i);
diff --git a/vip.c b/vip.c
index 3637294..d2a97a5 100644
--- a/vip.c
+++ b/vip.c
@@ -395,7 +395,7 @@ int vip_transfer_init(struct qdl_device *qdl, const char *vip_table_path)
 
 out_cleanup:
 	close(qdl->vip_data.signed_table_fd);
-	for (int i = 0; i < qdl->vip_data.chained_num - 1; ++i)
+	for (size_t i = 0; i < qdl->vip_data.chained_num - 1; ++i)
 		close(qdl->vip_data.chained_fds[i]);
 	return -1;
 }
@@ -403,7 +403,7 @@ int vip_transfer_init(struct qdl_device *qdl, const char *vip_table_path)
 void vip_transfer_deinit(struct qdl_device *qdl)
 {
 	close(qdl->vip_data.signed_table_fd);
-	for (int i = 0; i < qdl->vip_data.chained_num - 1; ++i)
+	for (size_t i = 0; i < qdl->vip_data.chained_num - 1; ++i)
 		close(qdl->vip_data.chained_fds[i]);
 }
 
@@ -412,7 +412,7 @@ static int vip_transfer_send_raw(struct qdl_device *qdl, int table_fd)
 	struct stat sb;
 	int ret;
 	void *buf;
-	size_t n;
+	ssize_t n;
 
 	ret = fstat(table_fd, &sb);
 	if (ret < 0) {