diff --git a/src/vlib/threads.c b/src/vlib/threads.c
index 36a8080..57ba39a 100644
--- a/src/vlib/threads.c
+++ b/src/vlib/threads.c
@@ -175,7 +175,6 @@
   vlib_thread_main_t *tm = &vlib_thread_main;
   vlib_worker_thread_t *w;
   vlib_thread_registration_t *tr;
-  cpu_set_t cpuset;
   u32 n_vlib_mains = 1;
   u32 first_index = 1;
   u32 i;
@@ -205,33 +204,26 @@
     }
 
   /* grab cpu for main thread */
-  if (tm->main_lcore == ~0)
-    {
-      /* if main-lcore is not set, we try to use lcore 1 */
-      if (clib_bitmap_get (avail_cpu, 1))
-	tm->main_lcore = 1;
-      else
-	tm->main_lcore = clib_bitmap_first_set (avail_cpu);
-      if (tm->main_lcore == (u8) ~ 0)
-	return clib_error_return (0, "no available cpus to be used for the"
-				  " main thread");
-    }
-  else
+  if (tm->main_lcore != ~0)
     {
       if (clib_bitmap_get (avail_cpu, tm->main_lcore) == 0)
 	return clib_error_return (0, "cpu %u is not available to be used"
 				  " for the main thread", tm->main_lcore);
+      avail_cpu = clib_bitmap_set (avail_cpu, tm->main_lcore, 0);
     }
-  avail_cpu = clib_bitmap_set (avail_cpu, tm->main_lcore, 0);
 
   /* assume that there is socket 0 only if there is no data from sysfs */
   if (!tm->cpu_socket_bitmap)
     tm->cpu_socket_bitmap = clib_bitmap_set (0, 0, 1);
 
   /* pin main thread to main_lcore  */
-  CPU_ZERO (&cpuset);
-  CPU_SET (tm->main_lcore, &cpuset);
-  pthread_setaffinity_np (pthread_self (), sizeof (cpu_set_t), &cpuset);
+  if (tm->main_lcore != ~0)
+    {
+      cpu_set_t cpuset;
+      CPU_ZERO (&cpuset);
+      CPU_SET (tm->main_lcore, &cpuset);
+      pthread_setaffinity_np (pthread_self (), sizeof (cpu_set_t), &cpuset);
+    }
 
   /* Set up thread 0 */
   vec_validate_aligned (vlib_worker_threads, 0, CLIB_CACHE_LINE_BYTES);
@@ -1652,12 +1644,17 @@
 clib_error_t *
 threads_init (vlib_main_t * vm)
 {
+  const vlib_thread_main_t *tm = vlib_get_thread_main ();
+
+  if (tm->main_lcore == ~0 && tm->n_vlib_mains > 1)
+    return clib_error_return (0, "Configuration error, a main core must "
+				 "be specified when using worker threads");
+
   return 0;
 }
 
 VLIB_INIT_FUNCTION (threads_init);
 
-
 static clib_error_t *
 show_clock_command_fn (vlib_main_t * vm,
 		       unformat_input_t * input, vlib_cli_command_t * cmd)
diff --git a/src/vlib/threads_cli.c b/src/vlib/threads_cli.c
index d14e9c5..9b30466 100644
--- a/src/vlib/threads_cli.c
+++ b/src/vlib/threads_cli.c
@@ -43,6 +43,7 @@
 show_threads_fn (vlib_main_t * vm,
 		 unformat_input_t * input, vlib_cli_command_t * cmd)
 {
+  const vlib_thread_main_t *tm = vlib_get_thread_main ();
   vlib_worker_thread_t *w;
   int i;
 
@@ -64,7 +65,7 @@
       line = format (line, "%-25U", format_sched_policy_and_priority, w->lwp);
 
       int cpu_id = w->cpu_id;
-      if (cpu_id > -1)
+      if (cpu_id > -1 && tm->main_lcore != ~0)
 	{
 	  int core_id = w->core_id;
 	  int numa_id = w->numa_id;
diff --git a/src/vpp/vnet/main.c b/src/vpp/vnet/main.c
index e9cef5e..f7e5382 100644
--- a/src/vpp/vnet/main.c
+++ b/src/vpp/vnet/main.c
@@ -112,7 +112,7 @@
   clib_mem_page_sz_t default_log2_hugepage_sz = CLIB_MEM_PAGE_SZ_UNKNOWN;
   unformat_input_t input, sub_input;
   u8 *s = 0, *v = 0;
-  int main_core = 1;
+  int main_core = ~0;
   cpu_set_t cpuset;
   void *main_heap;
 
@@ -316,9 +316,12 @@
   unformat_free (&input);
 
   /* set process affinity for main thread */
-  CPU_ZERO (&cpuset);
-  CPU_SET (main_core, &cpuset);
-  pthread_setaffinity_np (pthread_self (), sizeof (cpu_set_t), &cpuset);
+  if (main_core != ~0)
+    {
+      CPU_ZERO (&cpuset);
+      CPU_SET (main_core, &cpuset);
+      pthread_setaffinity_np (pthread_self (), sizeof (cpu_set_t), &cpuset);
+    }
 
   /* Set up the plugin message ID allocator right now... */
   vl_msg_api_set_first_available_msg_id (VL_MSG_MEMCLNT_LAST + 1);