diff --git a/src/internal/pthread_impl.h b/src/internal/pthread_impl.h
index 78b69cde..67b05753 100644
--- a/src/internal/pthread_impl.h
+++ b/src/internal/pthread_impl.h
@@ -115,6 +115,10 @@ void __acquire_ptc();
 void __release_ptc();
 void __inhibit_ptc();
 
+void __block_all_sigs(void *);
+void __block_app_sigs(void *);
+void __restore_sigs(void *);
+
 #define DEFAULT_STACK_SIZE 81920
 #define DEFAULT_GUARD_SIZE PAGE_SIZE
 
diff --git a/src/signal/block.c b/src/signal/block.c
new file mode 100644
index 00000000..d7f61001
--- /dev/null
+++ b/src/signal/block.c
@@ -0,0 +1,44 @@
+#include "pthread_impl.h"
+#include "syscall.h"
+#include <signal.h>
+
+static const unsigned long all_mask[] = {
+#if ULONG_MAX == 0xffffffff && _NSIG == 129
+	-1UL, -1UL, -1UL, -1UL
+#elif ULONG_MAX == 0xffffffff
+	-1UL, -1UL
+#else
+	-1UL
+#endif
+};
+
+static const unsigned long app_mask[] = {
+#if ULONG_MAX == 0xffffffff
+#if _NSIG == 65
+	0x7fffffff, 0xfffffffc
+#else
+	0x7fffffff, 0xfffffffc, -1UL, -1UL
+#endif
+#else
+#if _NSIG == 65
+	0xfffffffc7fffffff
+#else
+	0xfffffffc7fffffff, -1UL
+#endif
+#endif
+};
+
+void __block_all_sigs(void *set)
+{
+	__syscall(SYS_rt_sigprocmask, SIG_BLOCK, &all_mask, set, _NSIG/8);
+}
+
+void __block_app_sigs(void *set)
+{
+	__syscall(SYS_rt_sigprocmask, SIG_BLOCK, &app_mask, set, _NSIG/8);
+}
+
+void __restore_sigs(void *set)
+{
+	__syscall(SYS_rt_sigprocmask, SIG_SETMASK, set, 0, _NSIG/8);
+}
diff --git a/src/signal/raise.c b/src/signal/raise.c
index b24dc741..6fa43bef 100644
--- a/src/signal/raise.c
+++ b/src/signal/raise.c
@@ -8,10 +8,10 @@ int raise(int sig)
 {
 	int pid, tid, ret;
 	sigset_t set;
-	__syscall(SYS_rt_sigprocmask, SIG_BLOCK, SIGALL_SET, &set, _NSIG/8);
+	__block_app_sigs(&set);
 	tid = __syscall(SYS_gettid);
 	pid = __syscall(SYS_getpid);
 	ret = syscall(SYS_tgkill, pid, tid, sig);
-	__syscall(SYS_rt_sigprocmask, SIG_SETMASK, &set, 0, _NSIG/8);
+	__restore_sigs(&set);
 	return ret;
 }
diff --git a/src/signal/siglongjmp.c b/src/signal/siglongjmp.c
index bbdde796..a7bcca24 100644
--- a/src/signal/siglongjmp.c
+++ b/src/signal/siglongjmp.c
@@ -2,10 +2,10 @@
 #include <signal.h>
 #include <stdlib.h>
 #include "syscall.h"
+#include "pthread_impl.h"
 
 _Noreturn void siglongjmp(sigjmp_buf buf, int ret)
 {
-	if (buf->__fl) __syscall(SYS_rt_sigprocmask, SIG_SETMASK,
-		buf->__ss, 0, _NSIG/8);
+	if (buf->__fl) __restore_sigs(buf->__ss);
 	longjmp(buf->__jb, ret);
 }
diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c
index 6e49acdc..6c841be7 100644
--- a/src/thread/pthread_create.c
+++ b/src/thread/pthread_create.c
@@ -35,7 +35,7 @@ _Noreturn void pthread_exit(void *result)
 	 * This is important to ensure that dynamically allocated TLS
 	 * is not under-allocated/over-committed, and possibly for other
 	 * reasons as well. */
-	__syscall(SYS_rt_sigprocmask, SIG_BLOCK, SIGALL_SET, &set, _NSIG/8);
+	__block_all_sigs(&set);
 
 	/* Wait to unlock the kill lock, which governs functions like
 	 * pthread_kill which target a thread id, until signals have
@@ -51,7 +51,7 @@ _Noreturn void pthread_exit(void *result)
 	 * stdio cleanup code a consistent state. */
 	if (a_fetch_add(&libc.threads_minus_1, -1)==0) {
 		libc.threads_minus_1 = 0;
-		__syscall(SYS_rt_sigprocmask, SIG_SETMASK, &set, 0, _NSIG/8);
+		__restore_sigs(&set);
 		exit(0);
 	}
 
@@ -94,8 +94,7 @@ static int start(void *p)
 			self->detached = 2;
 			pthread_exit(0);
 		}
-		__syscall(SYS_rt_sigprocmask, SIG_SETMASK,
-			self->sigmask, 0, _NSIG/8);
+		__restore_sigs(self->sigmask);
 	}
 	if (self->unblock_cancel)
 		__syscall(SYS_rt_sigprocmask, SIG_UNBLOCK,
@@ -202,8 +201,7 @@ int pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attrp
 	}
 	if (attr._a_sched) {
 		do_sched = new->startlock[0] = 1;
-		__syscall(SYS_rt_sigprocmask, SIG_BLOCK,
-			SIGALL_SET, new->sigmask, _NSIG/8);
+		__block_app_sigs(new->sigmask);
 	}
 	new->unblock_cancel = self->cancel;
 	new->canary = self->canary;
@@ -214,8 +212,7 @@ int pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attrp
 	__release_ptc();
 
 	if (do_sched) {
-		__syscall(SYS_rt_sigprocmask, SIG_SETMASK,
-			new->sigmask, 0, _NSIG/8);
+		__restore_sigs(new->sigmask);
 	}
 
 	if (ret < 0) {