The error indicator for this syscall is -1, not 0.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 tests/tcg/multiarch/linux-test.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tests/tcg/multiarch/linux-test.c b/tests/tcg/multiarch/linux-test.c
index e80eccc0ce..6d2c02c5c0 100644
--- a/tests/tcg/multiarch/linux-test.c
+++ b/tests/tcg/multiarch/linux-test.c
@@ -503,8 +503,9 @@ static void test_shm(void)
 
     shmid = chk_error(shmget(IPC_PRIVATE, SHM_SIZE, IPC_CREAT | 0777));
     ptr = shmat(shmid, NULL, 0);
-    if (!ptr)
+    if (ptr == (void *)-1) {
         error("shmat");
+    }
 
     memset(ptr, 0, SHM_SIZE);
 
-- 
2.17.2