diff --git a/include/pthread.h b/include/pthread.h
index a94af29793..f2bac8cf70 100644
--- a/include/pthread.h
+++ b/include/pthread.h
@@ -137,8 +137,8 @@
 
 /* Definitions to map some non-standard, BSD thread management interfaces to
  * the non-standard Linux-like prctl() interface.  Since these are simple
- * mappings to prctl, they will return 0 sucess and -1 on failure with the
- * err number in errno.  This is an inconsistency with out pthread interfaces.
+ * mappings to prctl, they will return 0 on success and -1 on failure with the
+ * err number in errno.  This is an inconsistency with the pthread interfaces.
  */
 
 #define pthread_setname_np(thread, name) \
@@ -160,14 +160,13 @@ extern "C"
 
 typedef int             pthread_key_t;
 typedef FAR void       *pthread_addr_t;
-typedef pthread_addr_t  any_t;
 
 typedef pthread_addr_t (*pthread_startroutine_t)(pthread_addr_t);
 typedef pthread_startroutine_t pthread_func_t;
 
 struct pthread_attr_s
 {
-  size_t  stacksize;    /* Size of the stack allocated for the pthead */
+  size_t  stacksize;    /* Size of the stack allocated for the pthread */
   int16_t priority;     /* Priority of the pthread */
   uint8_t policy;       /* Pthread scheduler policy */
   uint8_t inheritsched; /* Inherit parent prio/policy? */
@@ -206,9 +205,9 @@ struct pthread_mutex_s
 typedef struct pthread_mutex_s pthread_mutex_t;
 
 #ifdef CONFIG_MUTEX_TYPES
-#  define PTHREAD_MUTEX_INITIALIZER {0, SEM_INITIALIZER(1), PTHREAD_MUTEX_DEFAULT, 0}
+#  define PTHREAD_MUTEX_INITIALIZER {-1, SEM_INITIALIZER(1), PTHREAD_MUTEX_DEFAULT, 0}
 #else
-#  define PTHREAD_MUTEX_INITIALIZER {0, SEM_INITIALIZER(1)}
+#  define PTHREAD_MUTEX_INITIALIZER {-1, SEM_INITIALIZER(1)}
 #endif
 
 struct pthread_barrierattr_s
@@ -307,7 +306,7 @@ void pthread_yield(void);
 
 /* Compare two thread IDs. */
 
-#define pthread_equal(t1,t2) (t1 == t2)
+#define pthread_equal(t1,t2) ((t1) == (t2))
 
 /* Thread scheduling parameters */
 
diff --git a/sched/pthread/pthread_condtimedwait.c b/sched/pthread/pthread_condtimedwait.c
index f6f8ec65bb..b9d266a763 100644
--- a/sched/pthread/pthread_condtimedwait.c
+++ b/sched/pthread/pthread_condtimedwait.c
@@ -270,7 +270,7 @@ int pthread_cond_timedwait(FAR pthread_cond_t *cond, FAR pthread_mutex_t *mutex,
                 {
                   /* Give up the mutex */
 
-                  mutex->pid = 0;
+                  mutex->pid = -1;
                   ret = pthread_givesemaphore((sem_t*)&mutex->sem);
                   if (ret)
                     {
diff --git a/sched/pthread/pthread_condwait.c b/sched/pthread/pthread_condwait.c
index 55856ccbc8..7460510a14 100644
--- a/sched/pthread/pthread_condwait.c
+++ b/sched/pthread/pthread_condwait.c
@@ -113,7 +113,7 @@ int pthread_cond_wait(FAR pthread_cond_t *cond, FAR pthread_mutex_t *mutex)
       sdbg("Give up mutex / take cond\n");
 
       sched_lock();
-      mutex->pid = 0;
+      mutex->pid = -1;
       ret = pthread_givesemaphore((sem_t*)&mutex->sem);
 
       /* Take the semaphore */
@@ -127,7 +127,7 @@ int pthread_cond_wait(FAR pthread_cond_t *cond, FAR pthread_mutex_t *mutex)
       ret |= pthread_takesemaphore((sem_t*)&mutex->sem);
       if (!ret)
         {
-          mutex->pid = getpid();;
+          mutex->pid = getpid();
         }
     }
 
diff --git a/sched/pthread/pthread_mutexdestroy.c b/sched/pthread/pthread_mutexdestroy.c
index b8abcb7168..3f768e1458 100644
--- a/sched/pthread/pthread_mutexdestroy.c
+++ b/sched/pthread/pthread_mutexdestroy.c
@@ -108,7 +108,7 @@ int pthread_mutex_destroy(FAR pthread_mutex_t *mutex)
 
       /* Is the semaphore available? */
 
-      if (mutex->pid != 0)
+      if (mutex->pid != -1)
         {
           ret = EBUSY;
         }
diff --git a/sched/pthread/pthread_mutexinit.c b/sched/pthread/pthread_mutexinit.c
index 1224e61b6a..0236830a06 100644
--- a/sched/pthread/pthread_mutexinit.c
+++ b/sched/pthread/pthread_mutexinit.c
@@ -115,7 +115,7 @@ int pthread_mutex_init(FAR pthread_mutex_t *mutex, FAR const pthread_mutexattr_t
 
       /* Indicate that the semaphore is not held by any thread. */
 
-      mutex->pid = 0;
+      mutex->pid = -1;
 
       /* Initialize the mutex like a semaphore with initial count = 1 */
 
diff --git a/sched/pthread/pthread_mutexunlock.c b/sched/pthread/pthread_mutexunlock.c
index 990f17de8a..0d340d08c7 100644
--- a/sched/pthread/pthread_mutexunlock.c
+++ b/sched/pthread/pthread_mutexunlock.c
@@ -148,7 +148,7 @@ int pthread_mutex_unlock(FAR pthread_mutex_t *mutex)
         {
           /* Nullify the pid and lock count then post the semaphore */
 
-          mutex->pid    = 0;
+          mutex->pid    = -1;
 #ifdef CONFIG_MUTEX_TYPES
           mutex->nlocks = 0;
 #endif