diff --git a/lib/thread.c b/lib/thread.c
index 948bc21..47a9dc4 100644
--- a/lib/thread.c
+++ b/lib/thread.c
@@ -269,7 +269,7 @@
 {
   struct cpu_thread_history *totals = args[0];
   struct vty *vty = args[1];
-  unsigned char *filter = args[2];
+  thread_type *filter = args[2];
   struct cpu_thread_history *a = bucket->data;
   
   a = bucket->data;
@@ -288,7 +288,7 @@
 }
 
 static void
-cpu_record_print(struct vty *vty, unsigned char filter)
+cpu_record_print(struct vty *vty, thread_type filter)
 {
   struct cpu_thread_history tmp;
   void *args[3] = {&tmp, vty, &filter};
@@ -323,7 +323,7 @@
       "Display filter (rwtexb)\n")
 {
   int i = 0;
-  unsigned char filter = 0xff;
+  thread_type filter = (thread_type) -1U;
 
   if (argc > 0)
     {
diff --git a/lib/thread.h b/lib/thread.h
index 1c324d8..b52bc54 100644
--- a/lib/thread.h
+++ b/lib/thread.h
@@ -57,11 +57,13 @@
   unsigned long alloc;
 };
 
+typedef unsigned char thread_type;
+
 /* Thread itself. */
 struct thread
 {
-  unsigned char type;		/* thread type */
-  unsigned char add_type;	/* thread type */
+  thread_type type;		/* thread type */
+  thread_type add_type;		/* thread type */
   struct thread *next;		/* next pointer of the thread */   
   struct thread *prev;		/* previous pointer of the thread */
   struct thread_master *master;	/* pointer to the struct thread_master. */
@@ -89,7 +91,7 @@
 #ifdef HAVE_RUSAGE
   struct time_stats cpu;
 #endif
-  unsigned char types;
+  thread_type types;
 };
 
 /* Clocks supported by Quagga */