diff --git a/tests/qtest/ide-test.c b/tests/qtest/ide-test.c
index 5e3e28aea2..4ea89c26c9 100644
--- a/tests/qtest/ide-test.c
+++ b/tests/qtest/ide-test.c
@@ -892,7 +892,7 @@ static void cdrom_pio_impl(int nblocks)
 
     /* Prepopulate the CDROM with an interesting pattern */
     generate_pattern(pattern, patt_len, ATAPI_BLOCK_SIZE);
-    fh = fopen(tmp_path, "w+");
+    fh = fopen(tmp_path, "wb+");
     ret = fwrite(pattern, ATAPI_BLOCK_SIZE, patt_blocks, fh);
     g_assert_cmpint(ret, ==, patt_blocks);
     fclose(fh);
@@ -993,7 +993,7 @@ static void test_cdrom_dma(void)
     prdt[0].size = cpu_to_le32(len | PRDT_EOT);
 
     generate_pattern(pattern, ATAPI_BLOCK_SIZE * 16, ATAPI_BLOCK_SIZE);
-    fh = fopen(tmp_path, "w+");
+    fh = fopen(tmp_path, "wb+");
     ret = fwrite(pattern, ATAPI_BLOCK_SIZE, 16, fh);
     g_assert_cmpint(ret, ==, 16);
     fclose(fh);