diff --git a/Userland/Libraries/LibC/bits/sighow.h b/Userland/Libraries/LibC/bits/sighow.h
new file mode 100644
index 0000000000..73d1a003f7
--- /dev/null
+++ b/Userland/Libraries/LibC/bits/sighow.h
@@ -0,0 +1,11 @@
+/*
+ * Copyright (c) 2021, the SerenityOS developers.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#define SIG_BLOCK 0
+#define SIG_UNBLOCK 1
+#define SIG_SETMASK 2
diff --git a/Userland/Libraries/LibC/signal.h b/Userland/Libraries/LibC/signal.h
index 6184ba0f67..8af4d4132a 100644
--- a/Userland/Libraries/LibC/signal.h
+++ b/Userland/Libraries/LibC/signal.h
@@ -7,6 +7,7 @@
 #pragma once
 
 #include <Kernel/API/POSIX/signal.h>
+#include <bits/sighow.h>
 #include <signal_numbers.h>
 #include <sys/types.h>