diff --git a/linux-user/signal.c b/linux-user/signal.c
index 79a39dc..26e0530 100644
--- a/linux-user/signal.c
+++ b/linux-user/signal.c
@@ -4115,7 +4115,7 @@ static target_ulong get_sigframe(struct
target_sigaction *ka,
    oldsp = env->gpr[1];

    if ((ka->sa_flags & TARGET_SA_ONSTACK) &&
-        (sas_ss_flags(oldsp))) {
+        (sas_ss_flags(oldsp)) == 0) {
        oldsp = (target_sigaltstack_used.ss_sp
                 + target_sigaltstack_used.ss_size);