diff --git a/sched/environ/env_dup.c b/sched/environ/env_dup.c
index 1745385daf..08b0e1b617 100644
--- a/sched/environ/env_dup.c
+++ b/sched/environ/env_dup.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * sched/environ/env_dup.c
  *
- *   Copyright (C) 2007, 2009, 2011, 2013 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007, 2009, 2011, 2013, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -82,7 +82,7 @@ int env_dup(FAR struct task_group_s *group)
   size_t envlen;
   int ret = OK;
 
-  DEBUGASSERT(group && ptcb && ptcb->group);
+  DEBUGASSERT(group != NULL && ptcb != NULL && ptcb->group != NULL);
 
   /* Pre-emption must be disabled throughout the following because the
    * environment may be shared.
@@ -92,22 +92,44 @@ int env_dup(FAR struct task_group_s *group)
 
   /* Does the parent task have an environment? */
 
-  if (ptcb->group && ptcb->group->tg_envp)
+  if (ptcb->group != NULL && ptcb->group->tg_envp != NULL)
     {
-      /* Yes..The parent task has an environment, duplicate it */
+      /* Yes.. The parent task has an environment allocation. */
 
       envlen = ptcb->group->tg_envsize;
-      envp   = (FAR char *)kumm_malloc(envlen);
-      if (!envp)
+      envp   = NULL;
+
+      /* A special case is that the parent has an "empty" environment
+       * allocation, i.e., there is an allocation in place but it
+       * contains no variable definitions and, hence, envlen == 0.
+       */
+
+      if (envlen > 0)
         {
-          ret = -ENOMEM;
-        }
-      else
-        {
-          group->tg_envsize = envlen;
-          group->tg_envp    = envp;
-          memcpy(envp, ptcb->group->tg_envp, envlen);
+          /* There is an environment, duplicate it */
+
+          envp = (FAR char *)kumm_malloc(envlen);
+          if (envp == NULL)
+            {
+              /* The parent's environment can not be inherited due to a
+               * failure in the allocation of the child environment.
+               */
+
+              envlen = 0;
+              ret    = -ENOMEM;
+            }
+          else
+            {
+             /* Duplicate the parent environment. */
+
+              memcpy(envp, ptcb->group->tg_envp, envlen);
+            }
         }
+
+      /* Save the size and child environment allocation. */
+
+      group->tg_envsize = envlen;
+      group->tg_envp    = envp;
     }
 
   sched_unlock();