diff --git a/test-tool/test_read6_beyond_eol.c b/test-tool/test_read6_beyond_eol.c
index b0020ef..4ceee34 100644
--- a/test-tool/test_read6_beyond_eol.c
+++ b/test-tool/test_read6_beyond_eol.c
@@ -37,7 +37,7 @@ test_read6_beyond_eol(void)
 
 	logging(LOG_VERBOSE, LOG_BLANK_LINE);
 	logging(LOG_VERBOSE, "Test READ6 1-255 blocks one block beyond the end");
-	for (i = 1; i <= 255; i++) {
+	for (i = 1; i <= 255 && i + 0U <= num_blocks + 1; i++) {
 		ret = read6(sd, NULL, num_blocks + 1 - i,
 			    i * block_size, block_size, NULL,
 			    EXPECT_LBA_OOB);
@@ -58,6 +58,10 @@ test_read6_beyond_eol(void)
 		CU_ASSERT_EQUAL(ret, 0);
 	}
 
+	if (num_blocks == 0) {
+		CU_PASS("LUN is too small for read-beyond-eol tests with READ6. Skipping test.\n");
+		return;
+	}
 
 	logging(LOG_VERBOSE, "Test READ6 2-255 blocks all but one block beyond the end");
 	for (i = 2; i <= 255; i++) {
diff --git a/test-tool/test_read6_simple.c b/test-tool/test_read6_simple.c
index b215dd3..c426393 100644
--- a/test-tool/test_read6_simple.c
+++ b/test-tool/test_read6_simple.c
@@ -54,7 +54,7 @@ test_read6_simple(void)
 	if (num_blocks > 0x200000) {
 		CU_PASS("LUN is too big for read-at-eol tests with READ6. Skipping test.\n");
 	} else {
-		for (i = 1; i <= 255; i++) {
+		for (i = 1; i <= 255 && i + 0U <= num_blocks; i++) {
 			if (maximum_transfer_length && maximum_transfer_length < i) {
 				break;
 			}