diff --git a/kernel/include/kernel/Process.h b/kernel/include/kernel/Process.h
index 66ce697200..cb83f00380 100644
--- a/kernel/include/kernel/Process.h
+++ b/kernel/include/kernel/Process.h
@@ -194,6 +194,7 @@ namespace Kernel
 		BAN::ErrorOr<long> sys_pthread_exit(void* value);
 		BAN::ErrorOr<long> sys_pthread_join(pthread_t thread, void** value);
 		BAN::ErrorOr<long> sys_pthread_self();
+		BAN::ErrorOr<long> sys_pthread_kill(pthread_t thread, int signal);
 
 		BAN::ErrorOr<long> sys_tcgetpgrp(int fd);
 		BAN::ErrorOr<long> sys_tcsetpgrp(int fd, pid_t pgid);
diff --git a/kernel/kernel/Process.cpp b/kernel/kernel/Process.cpp
index 1c2d5a48a7..1c281fdff2 100644
--- a/kernel/kernel/Process.cpp
+++ b/kernel/kernel/Process.cpp
@@ -2557,6 +2557,25 @@ namespace Kernel
 		return Thread::current().tid();
 	}
 
+	BAN::ErrorOr<long> Process::sys_pthread_kill(pthread_t tid, int signal)
+	{
+		if (signal != 0 && (signal < _SIGMIN || signal > _SIGMAX))
+			return BAN::Error::from_errno(EINVAL);
+
+		LockGuard _(m_process_lock);
+
+		for (auto* thread : m_threads)
+		{
+			if (thread->tid() != tid)
+				continue;
+			if (signal != 0)
+				thread->add_signal(signal);
+			return 0;
+		}
+
+		return BAN::Error::from_errno(ESRCH);
+	}
+
 	BAN::ErrorOr<long> Process::sys_tcgetpgrp(int fd)
 	{
 		LockGuard _(m_process_lock);
diff --git a/userspace/libraries/LibC/include/sys/syscall.h b/userspace/libraries/LibC/include/sys/syscall.h
index 9721653268..c8cf2e93ba 100644
--- a/userspace/libraries/LibC/include/sys/syscall.h
+++ b/userspace/libraries/LibC/include/sys/syscall.h
@@ -103,6 +103,7 @@ __BEGIN_DECLS
 	O(SYS_PTHREAD_EXIT,		pthread_exit)	\
 	O(SYS_PTHREAD_JOIN,		pthread_join)	\
 	O(SYS_PTHREAD_SELF,		pthread_self)	\
+	O(SYS_PTHREAD_KILL,		pthread_kill)	\
 	O(SYS_EPOLL_CREATE1,	epoll_create1)	\
 	O(SYS_EPOLL_CTL,		epoll_ctl)		\
 	O(SYS_EPOLL_PWAIT2,		epoll_pwait2)	\
diff --git a/userspace/libraries/LibC/signal.cpp b/userspace/libraries/LibC/signal.cpp
index e27e2355aa..86ed5685b6 100644
--- a/userspace/libraries/LibC/signal.cpp
+++ b/userspace/libraries/LibC/signal.cpp
@@ -38,9 +38,18 @@ void psignal(int signum, const char* message)
 		fprintf(stderr, "%s\n", strsignal(signum));
 }
 
+int pthread_kill(pthread_t thread, int sig)
+{
+	if (syscall(SYS_PTHREAD_KILL, thread, sig) == -1)
+		return errno;
+	return 0;
+}
+
 int pthread_sigmask(int how, const sigset_t* __restrict set, sigset_t* __restrict oset)
 {
-	return syscall(SYS_SIGPROCMASK, how, set, oset);
+	if (syscall(SYS_SIGPROCMASK, how, set, oset) == -1)
+		return errno;
+	return 0;
 }
 
 int raise(int sig)
@@ -138,7 +147,12 @@ int sigpending(sigset_t* set)
 
 int sigprocmask(int how, const sigset_t* __restrict set, sigset_t* __restrict oset)
 {
-	return pthread_sigmask(how, set, oset);
+	if (int error = pthread_sigmask(how, set, oset))
+	{
+		errno = error;
+		return -1;
+	}
+	return 0;
 }
 
 int sigrelse(int sig)