diff --git a/linux-user/qemu.h b/linux-user/qemu.h
index 4258e4162d2..aac03346270 100644
--- a/linux-user/qemu.h
+++ b/linux-user/qemu.h
@@ -151,6 +151,8 @@ typedef struct TaskState {
      */
     int signal_pending;
 
+    /* This thread's sigaltstack, if it has one */
+    struct target_sigaltstack sigaltstack_used;
 } __attribute__((aligned(16))) TaskState;
 
 extern char *exec_path;
diff --git a/linux-user/signal-common.h b/linux-user/signal-common.h
index 51030a93069..1df1068552f 100644
--- a/linux-user/signal-common.h
+++ b/linux-user/signal-common.h
@@ -19,7 +19,6 @@
 
 #ifndef SIGNAL_COMMON_H
 #define SIGNAL_COMMON_H
-extern struct target_sigaltstack target_sigaltstack_used;
 
 int on_sig_stack(unsigned long sp);
 int sas_ss_flags(unsigned long sp);
diff --git a/linux-user/hppa/signal.c b/linux-user/hppa/signal.c
index b6927ee6735..d1a58feeb36 100644
--- a/linux-user/hppa/signal.c
+++ b/linux-user/hppa/signal.c
@@ -111,10 +111,11 @@ void setup_rt_frame(int sig, struct target_sigaction *ka,
     abi_ulong frame_addr, sp, haddr;
     struct target_rt_sigframe *frame;
     int i;
+    TaskState *ts = (TaskState *)thread_cpu->opaque;
 
     sp = get_sp_from_cpustate(env);
     if ((ka->sa_flags & TARGET_SA_ONSTACK) && !sas_ss_flags(sp)) {
-        sp = (target_sigaltstack_used.ss_sp + 0x7f) & ~0x3f;
+        sp = (ts->sigaltstack_used.ss_sp + 0x7f) & ~0x3f;
     }
     frame_addr = QEMU_ALIGN_UP(sp, 64);
     sp = frame_addr + PARISC_RT_SIGFRAME_SIZE32;
diff --git a/linux-user/main.c b/linux-user/main.c
index a59ae9439de..8ffc5251955 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -180,6 +180,11 @@ void stop_all_tasks(void)
 void init_task_state(TaskState *ts)
 {
     ts->used = 1;
+    ts->sigaltstack_used = (struct target_sigaltstack) {
+        .ss_sp = 0,
+        .ss_size = 0,
+        .ss_flags = TARGET_SS_DISABLE,
+    };
 }
 
 CPUArchState *cpu_copy(CPUArchState *env)
diff --git a/linux-user/signal.c b/linux-user/signal.c
index 5cd237834d9..5ca6d62b15d 100644
--- a/linux-user/signal.c
+++ b/linux-user/signal.c
@@ -25,12 +25,6 @@
 #include "trace.h"
 #include "signal-common.h"
 
-struct target_sigaltstack target_sigaltstack_used = {
-    .ss_sp = 0,
-    .ss_size = 0,
-    .ss_flags = TARGET_SS_DISABLE,
-};
-
 static struct target_sigaction sigact_table[TARGET_NSIG];
 
 static void host_signal_handler(int host_signum, siginfo_t *info,
@@ -251,13 +245,17 @@ void set_sigmask(const sigset_t *set)
 
 int on_sig_stack(unsigned long sp)
 {
-    return (sp - target_sigaltstack_used.ss_sp
-            < target_sigaltstack_used.ss_size);
+    TaskState *ts = (TaskState *)thread_cpu->opaque;
+
+    return (sp - ts->sigaltstack_used.ss_sp
+            < ts->sigaltstack_used.ss_size);
 }
 
 int sas_ss_flags(unsigned long sp)
 {
-    return (target_sigaltstack_used.ss_size == 0 ? SS_DISABLE
+    TaskState *ts = (TaskState *)thread_cpu->opaque;
+
+    return (ts->sigaltstack_used.ss_size == 0 ? SS_DISABLE
             : on_sig_stack(sp) ? SS_ONSTACK : 0);
 }
 
@@ -266,17 +264,21 @@ abi_ulong target_sigsp(abi_ulong sp, struct target_sigaction *ka)
     /*
      * This is the X/Open sanctioned signal stack switching.
      */
+    TaskState *ts = (TaskState *)thread_cpu->opaque;
+
     if ((ka->sa_flags & TARGET_SA_ONSTACK) && !sas_ss_flags(sp)) {
-        return target_sigaltstack_used.ss_sp + target_sigaltstack_used.ss_size;
+        return ts->sigaltstack_used.ss_sp + ts->sigaltstack_used.ss_size;
     }
     return sp;
 }
 
 void target_save_altstack(target_stack_t *uss, CPUArchState *env)
 {
-    __put_user(target_sigaltstack_used.ss_sp, &uss->ss_sp);
+    TaskState *ts = (TaskState *)thread_cpu->opaque;
+
+    __put_user(ts->sigaltstack_used.ss_sp, &uss->ss_sp);
     __put_user(sas_ss_flags(get_sp_from_cpustate(env)), &uss->ss_flags);
-    __put_user(target_sigaltstack_used.ss_size, &uss->ss_size);
+    __put_user(ts->sigaltstack_used.ss_size, &uss->ss_size);
 }
 
 /* siginfo conversion */
@@ -708,12 +710,13 @@ abi_long do_sigaltstack(abi_ulong uss_addr, abi_ulong uoss_addr, abi_ulong sp)
 {
     int ret;
     struct target_sigaltstack oss;
+    TaskState *ts = (TaskState *)thread_cpu->opaque;
 
     /* XXX: test errors */
     if(uoss_addr)
     {
-        __put_user(target_sigaltstack_used.ss_sp, &oss.ss_sp);
-        __put_user(target_sigaltstack_used.ss_size, &oss.ss_size);
+        __put_user(ts->sigaltstack_used.ss_sp, &oss.ss_sp);
+        __put_user(ts->sigaltstack_used.ss_size, &oss.ss_size);
         __put_user(sas_ss_flags(sp), &oss.ss_flags);
     }
 
@@ -760,8 +763,8 @@ abi_long do_sigaltstack(abi_ulong uss_addr, abi_ulong uoss_addr, abi_ulong sp)
             }
         }
 
-        target_sigaltstack_used.ss_sp = ss.ss_sp;
-        target_sigaltstack_used.ss_size = ss.ss_size;
+        ts->sigaltstack_used.ss_sp = ss.ss_sp;
+        ts->sigaltstack_used.ss_size = ss.ss_size;
     }
 
     if (uoss_addr) {
