diff --git a/kernel/identity.cpp b/kernel/identity.cpp
index ce3346f5..f7f1449d 100644
--- a/kernel/identity.cpp
+++ b/kernel/identity.cpp
@@ -1,6 +1,6 @@
 /*******************************************************************************
 
-    Copyright(C) Jonas 'Sortie' Termansen 2013.
+    Copyright(C) Jonas 'Sortie' Termansen 2013, 2014.
 
     This file is part of Sortix.
 
@@ -22,8 +22,6 @@
 
 *******************************************************************************/
 
-#include <sortix/syscallnum.h>
-
 #include <sortix/kernel/kernel.h>
 #include <sortix/kernel/kthread.h>
 #include <sortix/kernel/process.h>
diff --git a/kernel/include/sortix/kernel/syscall.h b/kernel/include/sortix/kernel/syscall.h
index dfe06f13..a514e776 100644
--- a/kernel/include/sortix/kernel/syscall.h
+++ b/kernel/include/sortix/kernel/syscall.h
@@ -27,7 +27,7 @@
 
 #include <stddef.h>
 
-#include <sortix/syscallnum.h>
+#include <sortix/syscall.h>
 
 namespace Sortix {
 namespace Syscall {
diff --git a/kernel/include/sortix/syscallnum.h b/kernel/include/sortix/syscall.h
similarity index 98%
rename from kernel/include/sortix/syscallnum.h
rename to kernel/include/sortix/syscall.h
index e704d860..a548f677 100644
--- a/kernel/include/sortix/syscallnum.h
+++ b/kernel/include/sortix/syscall.h
@@ -17,8 +17,8 @@
     You should have received a copy of the GNU General Public License along with
     Sortix. If not, see <http://www.gnu.org/licenses/>.
 
-    sortix/syscallnum.h
-    Stores numerical constants for each available system call on this kernel.
+    sortix/syscall.h
+    Numeric constants identifying each system call.
 
 *******************************************************************************/
 
diff --git a/kernel/poll.cpp b/kernel/poll.cpp
index 3df62c71..618e4c0d 100644
--- a/kernel/poll.cpp
+++ b/kernel/poll.cpp
@@ -31,7 +31,6 @@
 
 #include <sortix/poll.h>
 #include <sortix/sigset.h>
-#include <sortix/syscallnum.h>
 #include <sortix/timespec.h>
 
 #include <sortix/kernel/copy.h>
diff --git a/kernel/syscall.cpp b/kernel/syscall.cpp
index 6dafbaaa..0bc2af78 100644
--- a/kernel/syscall.cpp
+++ b/kernel/syscall.cpp
@@ -24,7 +24,7 @@
 
 #include <stddef.h>
 
-#include <sortix/syscallnum.h>
+#include <sortix/syscall.h>
 
 #include <sortix/kernel/kernel.h>
 #include <sortix/kernel/process.h>
@@ -57,7 +57,6 @@ void Init()
 
 void Register(size_t index, void* function)
 {
-
 	if ( SYSCALL_MAX_NUM <= index )
 		PanicF("Attempted to register system call %p to index %zu, but "
 		       "SYSCALL_MAX_NUM = %zu", function, index, (size_t) SYSCALL_MAX_NUM);
diff --git a/libc/include/sys/syscall.h b/libc/include/sys/syscall.h
index eb793988..83f5bbe2 100644
--- a/libc/include/sys/syscall.h
+++ b/libc/include/sys/syscall.h
@@ -22,16 +22,16 @@
 
 *******************************************************************************/
 
-#if defined(__is_sortix_kernel)
-#error "This file is part of user-space and should not be built in kernel mode"
-#endif
-
 #ifndef INCLUDE_SYS_SYSCALL_H
 #define INCLUDE_SYS_SYSCALL_H
 
+#if !__STDC_HOSTED__
+#error "This file is part of user-space and should not be built into libk"
+#endif
+
 #include <sys/cdefs.h>
 
-#include <sortix/syscallnum.h>
+#include <sortix/syscall.h>
 
 /* Expand a macro and convert it to string. */
 #define SYSCALL_STRINGIFY_EXPAND(foo) #foo