diff --git a/include/posix/pthread.h b/include/posix/pthread.h
index a989f014ce0..350c28e641b 100644
--- a/include/posix/pthread.h
+++ b/include/posix/pthread.h
@@ -18,14 +18,14 @@
 #include <string.h>
 
 enum pthread_state {
+	/* The thread structure is unallocated and available for reuse. */
+	PTHREAD_TERMINATED = 0,
 	/* The thread is running and joinable. */
-	PTHREAD_JOINABLE = 0,
+	PTHREAD_JOINABLE,
 	/* The thread is running and detached. */
 	PTHREAD_DETACHED,
 	/* A joinable thread exited and its return code is available. */
-	PTHREAD_EXITED,
-	/* The thread structure is unallocated and available for reuse. */
-	PTHREAD_TERMINATED
+	PTHREAD_EXITED
 };
 
 struct posix_thread {
@@ -49,8 +49,8 @@ struct posix_thread {
 };
 
 /* Pthread detach/joinable */
-#define PTHREAD_CREATE_JOINABLE     0
-#define PTHREAD_CREATE_DETACHED     1
+#define PTHREAD_CREATE_JOINABLE     PTHREAD_JOINABLE
+#define PTHREAD_CREATE_DETACHED     PTHREAD_DETACHED
 
 /* Pthread cancellation */
 #define _PTHREAD_CANCEL_POS	0
diff --git a/lib/posix/Kconfig b/lib/posix/Kconfig
index 62bc3a34413..ef8e6063876 100644
--- a/lib/posix/Kconfig
+++ b/lib/posix/Kconfig
@@ -30,11 +30,11 @@ config PTHREAD_IPC
 
 if PTHREAD_IPC
 config MAX_PTHREAD_COUNT
-	int "Maximum pthread count in POSIX application"
+	int "Maximum simultaneously active pthread count in POSIX application"
 	default 5
 	range 0 255
 	help
-	  Mention maximum number of threads in POSIX compliant application.
+	  Maximum number of simultaneously active threads in a POSIX application.
 
 config SEM_VALUE_MAX
 	int "Maximum semaphore limit"
diff --git a/lib/posix/pthread.c b/lib/posix/pthread.c
index f1412d3895d..a2138bbccd3 100644
--- a/lib/posix/pthread.c
+++ b/lib/posix/pthread.c
@@ -35,7 +35,7 @@ static const pthread_attr_t init_pthread_attrs = {
 };
 
 static struct posix_thread posix_thread_pool[CONFIG_MAX_PTHREAD_COUNT];
-static u32_t pthread_num;
+PTHREAD_MUTEX_DEFINE(pthread_pool_lock);
 
 static bool is_posix_prio_valid(u32_t priority, int policy)
 {
@@ -132,6 +132,7 @@ int pthread_create(pthread_t *newthread, const pthread_attr_t *attr,
 		   void *(*threadroutine)(void *), void *arg)
 {
 	s32_t prio;
+	u32_t pthread_num;
 	pthread_condattr_t cond_attr;
 	struct posix_thread *thread;
 
@@ -145,6 +146,17 @@ int pthread_create(pthread_t *newthread, const pthread_attr_t *attr,
 		return EINVAL;
 	}
 
+	pthread_mutex_lock(&pthread_pool_lock);
+	for (pthread_num = 0;
+	    pthread_num < CONFIG_MAX_PTHREAD_COUNT; pthread_num++) {
+		thread = &posix_thread_pool[pthread_num];
+		if (thread->state == PTHREAD_TERMINATED) {
+			thread->state = PTHREAD_JOINABLE;
+			break;
+		}
+	}
+	pthread_mutex_unlock(&pthread_pool_lock);
+
 	if (pthread_num >= CONFIG_MAX_PTHREAD_COUNT) {
 		return EAGAIN;
 	}
@@ -166,7 +178,6 @@ int pthread_create(pthread_t *newthread, const pthread_attr_t *attr,
 
 	pthread_cond_init(&thread->state_cond, &cond_attr);
 	sys_slist_init(&thread->key_list);
-	pthread_num++;
 
 	*newthread = (pthread_t) k_thread_create(&thread->thread, attr->stack,
 						 attr->stacksize,