diff --git a/kernel/process.c b/kernel/process.c
index 2d3201f..43d6297 100644
--- a/kernel/process.c
+++ b/kernel/process.c
@@ -242,7 +242,7 @@ void process_launch(struct process *p)
 	list_push_tail(&ready_list, &p->node);
 }
 
-static void process_switch(int newstate)
+static void process_switch( process_state_t newstate )
 {
 	interrupt_block();
 
diff --git a/kernel/process.h b/kernel/process.h
index 37b7737..ad20fbe 100644
--- a/kernel/process.h
+++ b/kernel/process.h
@@ -15,11 +15,13 @@ See the file LICENSE for details.
 #include "x86.h"
 #include "fs.h"
 
-#define PROCESS_STATE_CRADLE  0
-#define PROCESS_STATE_READY   1
-#define PROCESS_STATE_RUNNING 2
-#define PROCESS_STATE_BLOCKED 3
-#define PROCESS_STATE_GRAVE   4
+typedef enum {
+	PROCESS_STATE_CRADLE,
+	PROCESS_STATE_READY,
+	PROCESS_STATE_RUNNING,
+	PROCESS_STATE_BLOCKED,
+	PROCESS_STATE_GRAVE,
+} process_state_t;
 
 #define PROCESS_MAX_OBJECTS 32
 #define PROCESS_MAX_PID 1024
@@ -29,7 +31,7 @@ See the file LICENSE for details.
 
 struct process {
 	struct list_node node;
-	int state;
+	process_state_t state;
 	int exitcode;
 	int exitreason;
 	struct pagetable *pagetable;