diff --git a/include/nuttx/sched.h b/include/nuttx/sched.h
index ae0700133f..a0eaaec2a1 100644
--- a/include/nuttx/sched.h
+++ b/include/nuttx/sched.h
@@ -507,6 +507,7 @@ struct task_group_s
   /* Environment variables **************************************************/
 
   FAR char **tg_envp;               /* Allocated environment strings        */
+  ssize_t    tg_envpc;              /* Maximum entries of environment array */
   ssize_t    tg_envc;               /* Number of environment strings        */
 #endif
 
diff --git a/sched/environ/env_dup.c b/sched/environ/env_dup.c
index 8ab1ea38e6..8a41b393e9 100644
--- a/sched/environ/env_dup.c
+++ b/sched/environ/env_dup.c
@@ -88,6 +88,7 @@ int env_dup(FAR struct task_group_s *group, FAR char * const *envcp)
         }
 
       group->tg_envc = envc;
+      group->tg_envpc = (envc + SCHED_ENVIRON_RESERVED + 1);
 
       /* A special case is that the parent has an "empty" environment
        * allocation, i.e., there is an allocation in place but it
@@ -98,7 +99,7 @@ int env_dup(FAR struct task_group_s *group, FAR char * const *envcp)
         {
           /* There is an environment, duplicate it */
 
-          envp = group_malloc(group, sizeof(*envp) * (envc + 1));
+          envp = group_malloc(group, sizeof(*envp) * group->tg_envpc);
           if (envp == NULL)
             {
               /* The parent's environment can not be inherited due to a
diff --git a/sched/environ/env_release.c b/sched/environ/env_release.c
index 9d4e510570..9b041aa7a3 100644
--- a/sched/environ/env_release.c
+++ b/sched/environ/env_release.c
@@ -83,8 +83,9 @@ void env_release(FAR struct task_group_s *group)
    * task group structure are reset to initial values.
    */
 
-  group->tg_envp = NULL;
-  group->tg_envc = 0;
+  group->tg_envp  = NULL;
+  group->tg_envpc = 0;
+  group->tg_envc  = 0;
 }
 
 #endif /* CONFIG_DISABLE_ENVIRON */
diff --git a/sched/environ/env_removevar.c b/sched/environ/env_removevar.c
index 93a10b0270..7ff4707ee9 100644
--- a/sched/environ/env_removevar.c
+++ b/sched/environ/env_removevar.c
@@ -86,14 +86,17 @@ void env_removevar(FAR struct task_group_s *group, ssize_t index)
     {
       group_free(group, group->tg_envp);
       group->tg_envp = NULL;
+      group->tg_envpc = 0;
     }
-  else
+  else if (group->tg_envc <=
+           (group->tg_envpc - SCHED_ENVIRON_RESERVED * 2))
     {
       /* Reallocate the environment to reclaim a little memory */
 
+      group->tg_envpc = group->tg_envc + SCHED_ENVIRON_RESERVED + 1;
+
       group->tg_envp = group_realloc(group, group->tg_envp,
-                                     sizeof(*group->tg_envp) *
-                                     (group->tg_envc + 1));
+         sizeof(*group->tg_envp) * group->tg_envpc);
       DEBUGASSERT(group->tg_envp != NULL);
     }
 }
diff --git a/sched/environ/env_setenv.c b/sched/environ/env_setenv.c
index bc5850dd0c..6180bc4fc3 100644
--- a/sched/environ/env_setenv.c
+++ b/sched/environ/env_setenv.c
@@ -71,7 +71,8 @@ int setenv(FAR const char *name, FAR const char *value, int overwrite)
   FAR struct task_group_s *group;
   FAR char *pvar;
   FAR char **envp;
-  ssize_t envc = 0;
+  ssize_t envc;
+  ssize_t envpc;
   ssize_t ret = OK;
   int varlen;
 
@@ -153,33 +154,41 @@ int setenv(FAR const char *name, FAR const char *value, int overwrite)
       goto errout_with_lock;
     }
 
-  if (group->tg_envp)
-    {
-      envc = group->tg_envc;
-      envp = group_realloc(group, group->tg_envp,
-                           sizeof(*envp) * (envc + 2));
-      if (envp == NULL)
-        {
-          ret = ENOMEM;
-          goto errout_with_var;
-        }
-    }
-  else
-    {
-      envp = group_malloc(group, sizeof(*envp) * 2);
-      if (envp == NULL)
-        {
-          ret = ENOMEM;
-          goto errout_with_var;
-        }
-    }
+  envc = group->tg_envc;
 
-  envp[envc++] = pvar;
-  envp[envc]   = NULL;
+  if (group->tg_envp == NULL)
+    {
+      envpc = SCHED_ENVIRON_RESERVED + 2;
+
+      envp = group_malloc(group, sizeof(*envp) * envpc);
+      if (envp == NULL)
+        {
+          ret = ENOMEM;
+          goto errout_with_var;
+        }
+
+      group->tg_envp  = envp;
+      group->tg_envpc = envpc;
+    }
+  else if (envc >= group->tg_envpc - 1)
+    {
+      envpc = envc + SCHED_ENVIRON_RESERVED + 2;
+
+      envp = group_realloc(group, group->tg_envp, sizeof(*envp) * envpc);
+      if (envp == NULL)
+        {
+          ret = ENOMEM;
+          goto errout_with_var;
+        }
+
+      group->tg_envp  = envp;
+      group->tg_envpc = envpc;
+    }
 
   /* Save the new buffer and count */
 
-  group->tg_envp = envp;
+  group->tg_envp[envc++] = pvar;
+  group->tg_envp[envc]   = NULL;
   group->tg_envc = envc;
 
   /* Now, put the new name=value string into the environment buffer */
diff --git a/sched/environ/environ.h b/sched/environ/environ.h
index 615306c736..e1846116db 100644
--- a/sched/environ/environ.h
+++ b/sched/environ/environ.h
@@ -37,6 +37,8 @@
 #  define env_release(group)   (0)
 #else
 
+#  define SCHED_ENVIRON_RESERVED (4)
+
 /****************************************************************************
  * Public Data
  ****************************************************************************/