diff --git a/test-tool/0182_writesame10_beyondeol.c b/test-tool/0182_writesame10_beyondeol.c
index d39d39d..3ea149b 100644
--- a/test-tool/0182_writesame10_beyondeol.c
+++ b/test-tool/0182_writesame10_beyondeol.c
@@ -28,7 +28,7 @@ int T0182_writesame10_beyondeol(const char *initiator, const char *url, int data
 	int ret, i, lun;
 	uint32_t block_size;
 	uint64_t num_blocks;
-	char buf[512];
+	unsigned char buf[512];
 
 	printf("0182_writesame10_beyondeol:\n");
 	printf("=======================\n");
diff --git a/test-tool/0183_writesame10_wrprotect.c b/test-tool/0183_writesame10_wrprotect.c
index f4265b4..33bc35a 100644
--- a/test-tool/0183_writesame10_wrprotect.c
+++ b/test-tool/0183_writesame10_wrprotect.c
@@ -28,7 +28,7 @@ int T0183_writesame10_wrprotect(const char *initiator, const char *url, int data
 	int ret, i, lun;
 	uint32_t block_size;
 	uint64_t num_blocks;
-	char buf[512];
+	unsigned char buf[512];
 
 	printf("0183_writesame10_wrptotect:\n");
 	printf("=======================\n");
diff --git a/test-tool/0184_writesame10_0blocks.c b/test-tool/0184_writesame10_0blocks.c
index 7a053ef..62c539d 100644
--- a/test-tool/0184_writesame10_0blocks.c
+++ b/test-tool/0184_writesame10_0blocks.c
@@ -25,7 +25,7 @@ int T0184_writesame10_0blocks(const char *initiator, const char *url, int data_l
 	struct iscsi_context *iscsi;
 	struct scsi_task *task;
 	struct scsi_readcapacity16 *rc16;
-	int ret, i, lun;
+	int ret, lun;
 	uint32_t block_size;
 	uint64_t num_blocks;
 	unsigned char buf[512];
diff --git a/test-tool/0193_writesame16_wrprotect.c b/test-tool/0193_writesame16_wrprotect.c
index dbd94f3..02051ca 100644
--- a/test-tool/0193_writesame16_wrprotect.c
+++ b/test-tool/0193_writesame16_wrprotect.c
@@ -28,7 +28,7 @@ int T0193_writesame16_wrprotect(const char *initiator, const char *url, int data
 	int ret, i, lun;
 	uint32_t block_size;
 	uint64_t num_blocks;
-	char buf[512];
+	unsigned char buf[512];
 
 	printf("0193_writesame16_wrptotect:\n");
 	printf("=======================\n");
diff --git a/test-tool/0194_writesame16_0blocks.c b/test-tool/0194_writesame16_0blocks.c
index e0ec6e0..00b569c 100644
--- a/test-tool/0194_writesame16_0blocks.c
+++ b/test-tool/0194_writesame16_0blocks.c
@@ -25,7 +25,7 @@ int T0194_writesame16_0blocks(const char *initiator, const char *url, int data_l
 	struct iscsi_context *iscsi;
 	struct scsi_task *task;
 	struct scsi_readcapacity16 *rc16;
-	int ret, i, lun;
+	int ret, lun;
 	uint32_t block_size;
 	uint64_t num_blocks;
 	unsigned char buf[512];