diff --git a/tests/test_virgl_transfer.c b/tests/test_virgl_transfer.c
index 6748e50..d185ae5 100644
--- a/tests/test_virgl_transfer.c
+++ b/tests/test_virgl_transfer.c
@@ -733,7 +733,7 @@ START_TEST(virgl_test_transfer_to_staging_without_iov_fails)
   static const unsigned bufsize = 50;
   struct virgl_context ctx;
   struct virgl_resource res;
-  struct pipe_box box;
+  struct pipe_box box = {.width = bufsize, .height = 1, .depth = 1};
   int ret;
 
   ret = testvirgl_init_ctx_cmdbuf(&ctx);
@@ -760,7 +760,7 @@ START_TEST(virgl_test_transfer_to_staging_with_iov_succeeds)
   static const unsigned bufsize = 50;
   struct virgl_context ctx = {0};
   struct virgl_resource res = {0};
-  struct pipe_box box = {0};
+  struct pipe_box box = {.width = bufsize, .height = 1, .depth = 1};
   int ret;
 
   ret = testvirgl_init_ctx_cmdbuf(&ctx);
@@ -789,7 +789,7 @@ START_TEST(virgl_test_copy_transfer_from_staging_without_iov_fails)
   struct virgl_context ctx = {0};
   struct virgl_resource src_res = {0};
   struct virgl_resource dst_res = {0};
-  struct pipe_box box = {0};
+  struct pipe_box box = {.width = bufsize, .height = 1, .depth = 1};
   int ret;
 
   ret = testvirgl_init_ctx_cmdbuf(&ctx);
@@ -824,7 +824,7 @@ START_TEST(virgl_test_copy_transfer_from_staging_with_iov_succeeds)
   struct virgl_context ctx = {0};
   struct virgl_resource src_res = {0};
   struct virgl_resource dst_res = {0};
-  struct pipe_box box = {0};
+  struct pipe_box box = {.width = bufsize, .height = 1, .depth = 1};
   int ret;
 
   ret = testvirgl_init_ctx_cmdbuf(&ctx);
@@ -854,25 +854,25 @@ END_TEST
 
 START_TEST(virgl_test_copy_transfer_to_staging_without_iov_fails)
 {
+  static const unsigned bufsize = 50;
   const unsigned synchronized = 1;
   struct virgl_context ctx = {0};
   struct virgl_resource src_res = {0};
   struct virgl_resource dst_res = {0};
-  struct pipe_box box = {0};
+  struct pipe_box box = {.width = bufsize, .height = 1, .depth = 1};
   int ret;
 
   ret = testvirgl_init_ctx_cmdbuf(&ctx);
   ck_assert_int_eq(ret, 0);
 
-  ret = testvirgl_create_backed_simple_buffer(&src_res, 1, 50, VIRGL_BIND_STAGING);
+  ret = testvirgl_create_backed_simple_buffer(&src_res, 1, bufsize, VIRGL_BIND_STAGING);
   ck_assert_int_eq(ret, 0);
   virgl_renderer_ctx_attach_resource(ctx.ctx_id, src_res.handle);
 
-  ret = testvirgl_create_unbacked_simple_buffer(&dst_res, 2, 50, VIRGL_BIND_STAGING);
+  ret = testvirgl_create_unbacked_simple_buffer(&dst_res, 2, bufsize, VIRGL_BIND_STAGING);
   ck_assert_int_eq(ret, 0);
   virgl_renderer_ctx_attach_resource(ctx.ctx_id, dst_res.handle);
 
-  box.width = 50;
   virgl_encoder_copy_transfer(&ctx, &dst_res, 0, 0, &box, &src_res, 0, synchronized);
 
   ret = virgl_renderer_submit_cmd(ctx.cbuf->buf, ctx.ctx_id, ctx.cbuf->cdw);
@@ -885,27 +885,28 @@ START_TEST(virgl_test_copy_transfer_to_staging_without_iov_fails)
   testvirgl_fini_ctx_cmdbuf(&ctx);
 }
 END_TEST
+
 START_TEST(virgl_test_copy_transfer_to_staging_with_iov_succeeds)
 {
+  static const unsigned bufsize = 50;
   const unsigned synchronized = 1;
   struct virgl_context ctx = {0};
   struct virgl_resource src_res = {0};
   struct virgl_resource dst_res = {0};
-  struct pipe_box box = {0};
+  struct pipe_box box = {.width = bufsize, .height = 1, .depth = 1};
   int ret;
 
   ret = testvirgl_init_ctx_cmdbuf(&ctx);
   ck_assert_int_eq(ret, 0);
 
-  ret = testvirgl_create_backed_simple_buffer(&src_res, 1, 50, VIRGL_BIND_STAGING);
+  ret = testvirgl_create_backed_simple_buffer(&src_res, 1, bufsize, VIRGL_BIND_STAGING);
   ck_assert_int_eq(ret, 0);
   virgl_renderer_ctx_attach_resource(ctx.ctx_id, src_res.handle);
 
-  ret = testvirgl_create_backed_simple_buffer(&dst_res, 2, 50, VIRGL_BIND_STAGING);
+  ret = testvirgl_create_backed_simple_buffer(&dst_res, 2, bufsize, VIRGL_BIND_STAGING);
   ck_assert_int_eq(ret, 0);
   virgl_renderer_ctx_attach_resource(ctx.ctx_id, dst_res.handle);
 
-  box.width = 50;
   virgl_encoder_copy_transfer(&ctx, &dst_res, 0, 0, &box, &src_res, 0, synchronized);
 
   ret = virgl_renderer_submit_cmd(ctx.cbuf->buf, ctx.ctx_id, ctx.cbuf->cdw);