diff --git a/lib/libc/syscall.c b/lib/libc/syscall.c
index a489e46..b1aaf7e 100644
--- a/lib/libc/syscall.c
+++ b/lib/libc/syscall.c
@@ -152,19 +152,19 @@ OSSysCtl(const char *node, void *oldvar, void *newvar)
 }
 
 int
-OS_FSMount(const char *mntpt, const char *device, uint64_t flags)
+OSFSMount(const char *mntpt, const char *device, uint64_t flags)
 {
     return syscall(SYSCALL_FSMOUNT, mntpt, device, flags);
 }
 
 int
-OS_FSUnmount(const char *mntpt)
+OSFSUnmount(const char *mntpt)
 {
     return syscall(SYSCALL_FSUNMOUNT, mntpt);
 }
 
 int
-OS_FSInfo(struct statfs *info, uint64_t max)
+OSFSInfo(struct statfs *info, uint64_t max)
 {
     return syscall(SYSCALL_FSINFO, info, max);
 }
diff --git a/sys/include/loader.h b/sys/include/loader.h
index 761deb3..e625712 100644
--- a/sys/include/loader.h
+++ b/sys/include/loader.h
@@ -2,6 +2,9 @@
 #ifndef __SYS_LOADER_H__
 #define __SYS_LOADER_H__
 
+#include <sys/elf64.h>
+
+bool Loader_CheckHeader(const Elf64_Ehdr *ehdr);
 bool Loader_Load(Thread *thr, VNode *vn, void *buf, uint64_t len);
 
 #endif /* __SYS_LOADER_H__ */
diff --git a/sys/include/sysctl.h b/sys/include/sysctl.h
index bc096fa..2a8f1a8 100644
--- a/sys/include/sysctl.h
+++ b/sys/include/sysctl.h
@@ -65,6 +65,7 @@ SYSCTL_LIST
 
 uint64_t SysCtl_GetType(const char *node);
 void *SysCtl_GetObject(const char *node);
+uint64_t SysCtl_SetObject(const char *node, void *obj);
 
 #endif /* __SYS_SYSCTL_H__ */
 
diff --git a/sys/kern/syscall.c b/sys/kern/syscall.c
index b5dc17a..5922153 100644
--- a/sys/kern/syscall.c
+++ b/sys/kern/syscall.c
@@ -73,33 +73,37 @@ Syscall_Spawn(uint64_t user_path)
 
     status = CopyStrIn(user_path, &path, sizeof(path));
     if (status != 0)
-	return status;
+	return SYSCALL_PACK(status, 0);
 
     Log(syscall, "Spawn(%s)\n", path);
 
     pg = PAlloc_AllocPage();
     if (!pg) {
-	return ENOMEM;
+	return SYSCALL_PACK(ENOMEM, 0);
     }
 
     file = VFS_Lookup(path);
     if (!file) {
 	// Free
-	return ENOENT;
+	return SYSCALL_PACK(ENOENT, 0);
     }
 
     status = VFS_Open(file);
     if (status < 0) {
 	Log(syscall, "Error VFS_Open\n");
 	// Release & free
-	return status;
+	return SYSCALL_PACK(status, 0);
     }
 
     status = VFS_Read(file, pg, 0, 1024);
     if (status < 0) {
 	Log(syscall, "Error VFS_Read\n");
 	// Release & free
-	return status;
+	return SYSCALL_PACK(status, 0);
+    }
+
+    if (!Loader_CheckHeader(pg)) {
+	return SYSCALL_PACK(EINVAL, 0);
     }
 
     cur = Sched_Current();
@@ -121,7 +125,7 @@ Syscall_Spawn(uint64_t user_path)
 
     Sched_SetRunnable(thr);
 
-    return proc->pid;
+    return SYSCALL_PACK(0, proc->pid);
 }
 
 uint64_t
@@ -573,7 +577,44 @@ Syscall_SysCtl(uint64_t user_node, uint64_t user_oldval, uint64_t user_newval)
 	return status;
     }
 
-    // XXX: Support setting
+    if (user_newval == 0) {
+	return 0;
+    }
+
+    switch (scType) {
+	case SYSCTL_TYPE_STR: {
+	    SysCtlString scStr;
+	    status = CopyIn(user_newval, &scStr, sizeof(scStr));
+	    if (status != 0) {
+		return status;
+	    }
+	    status = SysCtl_SetObject(node, (void *)&scStr);
+	    break;
+	}
+	case SYSCTL_TYPE_INT: {
+	    SysCtlInt scInt;
+	    status = CopyIn(user_newval, &scInt, sizeof(scInt));
+	    if (status != 0) {
+		return status;
+	    }
+	    status = SysCtl_SetObject(node, (void *)&scInt);
+	    break;
+	}
+	case SYSCTL_TYPE_BOOL: {
+	    SysCtlBool scBool;
+	    status = CopyIn(user_newval, &scBool, sizeof(scBool));
+	    if (status != 0) {
+		return status;
+	    }
+	    status = SysCtl_SetObject(node, (void *)&scBool);
+	    break;
+	}
+	default: {
+	    status = SYSCALL_PACK(ENOENT, 0);
+	}
+    }
+
+    return status;
 }
 
 uint64_t
diff --git a/sys/kern/sysctl.c b/sys/kern/sysctl.c
index ee60ab4..a00562e 100644
--- a/sys/kern/sysctl.c
+++ b/sys/kern/sysctl.c
@@ -75,6 +75,39 @@ SysCtl_GetObject(const char *node)
     return SYSCTLTable[i].node;
 }
 
+uint64_t
+SysCtl_SetObject(const char *node, void *obj)
+{
+    int i = SysCtl_Lookup(node);
+    if (i == -1) {
+	return -1;
+    }
+
+    // Validate inputs
+
+    if (SYSCTLTable[i].flags == SYSCTL_FLAG_RO) {
+	kprintf("Sysctl node is read-only!\n");
+	return -1;
+    }
+
+    switch (SYSCTLTable[i].type) {
+	case SYSCTL_TYPE_STR: {
+	    SysCtlString *val = (SysCtlString *)SYSCTLTable[i].node;
+	    memcpy(val, obj, sizeof(*val));
+	}
+	case SYSCTL_TYPE_INT: {
+	    SysCtlInt *val = (SysCtlInt *)SYSCTLTable[i].node;
+	    memcpy(val, obj, sizeof(*val));
+	}
+	case SYSCTL_TYPE_BOOL: {
+	    SysCtlBool *val = (SysCtlBool *)SYSCTLTable[i].node;
+	    memcpy(val, obj, sizeof(*val));
+	}
+    }
+
+    return 0;
+}
+
 void
 Debug_SysCtl(int argc, const char *argv[])
 {