diff --git a/libc/Makefile b/libc/Makefile
index 561cd3d0..0f2775b5 100644
--- a/libc/Makefile
+++ b/libc/Makefile
@@ -302,6 +302,7 @@ setlocale.o \
 settermmode.o \
 setuid.o \
 sfork.o \
+sigaction.o \
 SIG_DFL.o \
 SIG_ERR.o \
 SIG_IGN.o \
diff --git a/libc/sigaction.cpp b/libc/sigaction.cpp
new file mode 100644
index 00000000..b35442db
--- /dev/null
+++ b/libc/sigaction.cpp
@@ -0,0 +1,73 @@
+/*******************************************************************************
+
+    Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2013.
+
+    This file is part of the Sortix C Library.
+
+    The Sortix C Library is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or (at your
+    option) any later version.
+
+    The Sortix C Library is distributed in the hope that it will be useful, but
+    WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+    or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+    License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
+
+    sigaction.cpp
+    Set the action that happens when a signal is triggered.
+
+*******************************************************************************/
+
+#include <stdio.h>
+#include <signal.h>
+
+const int MAX_SIGNALS = 128;
+extern sighandler_t handlers[MAX_SIGNALS];
+
+// TODO: Actually implement the sigaction interface for real.
+int sigaction(int signum, const struct sigaction* restrict act,
+              struct sigaction* restrict oldact)
+{
+	if ( !act )
+	{
+		// TODO: set oldact->sa_mask here?
+		oldact->sa_sigaction = NULL;
+		oldact->sa_handler = handlers[signum];
+		oldact->sa_flags = 0;
+		return 0;
+	}
+	int understood_flags = SA_SIGINFO | SA_RESTART;
+	if ( act->sa_flags & ~understood_flags )
+	{
+		fprintf(stderr, "%s:%u sigaction with unsupported flags 0x%x, ignoring "
+		                "hoping they aren't needed.\n", __FILE__, __LINE__,
+		                act->sa_flags & ~understood_flags);
+	}
+	if ( act->sa_flags & SA_RESTART )
+		/* TODO: Actually implement this. Signals are a bit rare on Sortix right
+		         now, so it doesn't matter much that system calls don't restart
+		         on Sortix, so pretend that they do. */ {};
+	if ( act->sa_flags & SA_SIGINFO )
+	{
+		fprintf(stderr, "%s:%u sigaction with unsupported SA_SIGINFO, ignoring "
+		                "hoping the signal never happens.\n", __FILE__,
+		                __LINE__);
+		return 0;
+	}
+	sighandler_t new_handler = act->sa_handler;
+	sighandler_t old_handler = signal(signum, new_handler);
+	if ( old_handler == SIG_ERR )
+		return -1;
+	if ( oldact )
+	{
+		// TODO: set oldact->sa_mask here?
+		oldact->sa_sigaction = NULL;
+		oldact->sa_handler = old_handler;
+		oldact->sa_flags = 0;
+	}
+	return 0;
+}