diff --git a/src/api/sockets.c b/src/api/sockets.c
index 1011cfb4..2a767759 100644
--- a/src/api/sockets.c
+++ b/src/api/sockets.c
@@ -85,7 +85,7 @@
 
 #define API_SELECT_CB_VAR_REF(name)               API_VAR_REF(name)
 #define API_SELECT_CB_VAR_DECLARE(name)           API_VAR_DECLARE(struct lwip_select_cb, name)
-#define API_SELECT_CB_VAR_ALLOC(name, retblock)    API_VAR_ALLOC_EXT(struct lwip_select_cb, MEMP_SELECT_CB, name, retblock)
+#define API_SELECT_CB_VAR_ALLOC(name, retblock)   API_VAR_ALLOC_EXT(struct lwip_select_cb, MEMP_SELECT_CB, name, retblock)
 #define API_SELECT_CB_VAR_FREE(name)              API_VAR_FREE(MEMP_SELECT_CB, name)
 
 #if LWIP_IPV4
@@ -1844,7 +1844,6 @@ lwip_select(int maxfdp1, fd_set *readset, fd_set *writeset, fd_set *exceptset,
   int nready;
   fd_set lreadset, lwriteset, lexceptset;
   u32_t msectimeout;
-  API_SELECT_CB_VAR_DECLARE(select_cb);
   int i;
   int maxfdp2;
 #if LWIP_NETCONN_SEM_PER_THREAD
@@ -1856,8 +1855,6 @@ lwip_select(int maxfdp1, fd_set *readset, fd_set *writeset, fd_set *exceptset,
   SYS_ARCH_DECL_PROTECT(lev);
   LWIP_SOCKET_SELECT_DECL_PROTECT(lev2);
 
-  API_SELECT_CB_VAR_ALLOC(select_cb, set_errno(ENOMEM); return -1);
-
   LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_select(%d, %p, %p, %p, tvsec=%"S32_F" tvusec=%"S32_F")\n",
                   maxfdp1, (void *)readset, (void *) writeset, (void *) exceptset,
                   timeout ? (s32_t)timeout->tv_sec : (s32_t)-1,
@@ -1865,7 +1862,6 @@ lwip_select(int maxfdp1, fd_set *readset, fd_set *writeset, fd_set *exceptset,
 
   if ((maxfdp1 < 0) || (maxfdp1 > (FD_SETSIZE + LWIP_SOCKET_OFFSET))) {
     set_errno(EINVAL);
-    API_SELECT_CB_VAR_FREE(select_cb);
     return -1;
   }
 
@@ -1876,192 +1872,194 @@ lwip_select(int maxfdp1, fd_set *readset, fd_set *writeset, fd_set *exceptset,
   nready = lwip_selscan(maxfdp1, readset, writeset, exceptset, &lreadset, &lwriteset, &lexceptset);
 
   if (nready < 0) {
+    /* one of the sockets in one of the fd_sets was invalid */
     set_errno(EBADF);
     lwip_select_dec_sockets_used(maxfdp1, &used_sockets);
-    API_SELECT_CB_VAR_FREE(select_cb);
     return -1;
-  }
-
-  /* If we don't have any current events, then suspend if we are supposed to */
-  if (!nready) {
+  } else if (nready > 0) {
+    /* one or more sockets are set, no need to wait */
+    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_select: nready=%d\n", nready));
+  } else {
+    /* If we don't have any current events, then suspend if we are supposed to */
     if (timeout && timeout->tv_sec == 0 && timeout->tv_usec == 0) {
       LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_select: no timeout, returning 0\n"));
       /* This is OK as the local fdsets are empty and nready is zero,
          or we would have returned earlier. */
-      goto return_copy_fdsets;
-    }
+    } else {
+      /* None ready: add our semaphore to list:
+         We don't actually need any dynamic memory. Our entry on the
+         list is only valid while we are in this function, so it's ok
+         to use local variables (unless we're running in MPU compatible
+         mode). */
+      API_SELECT_CB_VAR_DECLARE(select_cb);
+      API_SELECT_CB_VAR_ALLOC(select_cb, set_errno(ENOMEM); return -1);
 
-    /* None ready: add our semaphore to list:
-       We don't actually need any dynamic memory. Our entry on the
-       list is only valid while we are in this function, so it's ok
-       to use local variables. */
-
-    API_SELECT_CB_VAR_REF(select_cb).next = NULL;
-    API_SELECT_CB_VAR_REF(select_cb).prev = NULL;
-    API_SELECT_CB_VAR_REF(select_cb).readset = readset;
-    API_SELECT_CB_VAR_REF(select_cb).writeset = writeset;
-    API_SELECT_CB_VAR_REF(select_cb).exceptset = exceptset;
-    API_SELECT_CB_VAR_REF(select_cb).sem_signalled = 0;
+      API_SELECT_CB_VAR_REF(select_cb).next = NULL;
+      API_SELECT_CB_VAR_REF(select_cb).prev = NULL;
+      API_SELECT_CB_VAR_REF(select_cb).readset = readset;
+      API_SELECT_CB_VAR_REF(select_cb).writeset = writeset;
+      API_SELECT_CB_VAR_REF(select_cb).exceptset = exceptset;
+      API_SELECT_CB_VAR_REF(select_cb).sem_signalled = 0;
 #if LWIP_NETCONN_SEM_PER_THREAD
-    API_SELECT_CB_VAR_REF(select_cb).sem = LWIP_NETCONN_THREAD_SEM_GET();
+      API_SELECT_CB_VAR_REF(select_cb).sem = LWIP_NETCONN_THREAD_SEM_GET();
 #else /* LWIP_NETCONN_SEM_PER_THREAD */
-    if (sys_sem_new(&API_SELECT_CB_VAR_REF(select_cb).sem, 0) != ERR_OK) {
-      /* failed to create semaphore */
-      set_errno(ENOMEM);
-      lwip_select_dec_sockets_used(maxfdp1, &used_sockets);
-      API_SELECT_CB_VAR_FREE(select_cb);
-      return -1;
-    }
+      if (sys_sem_new(&API_SELECT_CB_VAR_REF(select_cb).sem, 0) != ERR_OK) {
+        /* failed to create semaphore */
+        set_errno(ENOMEM);
+        lwip_select_dec_sockets_used(maxfdp1, &used_sockets);
+        API_SELECT_CB_VAR_FREE(select_cb);
+        return -1;
+      }
 #endif /* LWIP_NETCONN_SEM_PER_THREAD */
 
-    /* Protect the select_cb_list */
-    LWIP_SOCKET_SELECT_PROTECT(lev2);
+      /* Protect the select_cb_list */
+      LWIP_SOCKET_SELECT_PROTECT(lev2);
 
-    /* Put this select_cb on top of list */
-    API_SELECT_CB_VAR_REF(select_cb).next = select_cb_list;
-    if (select_cb_list != NULL) {
-      select_cb_list->prev = &API_SELECT_CB_VAR_REF(select_cb);
-    }
-    select_cb_list = &API_SELECT_CB_VAR_REF(select_cb);
+      /* Put this select_cb on top of list */
+      API_SELECT_CB_VAR_REF(select_cb).next = select_cb_list;
+      if (select_cb_list != NULL) {
+        select_cb_list->prev = &API_SELECT_CB_VAR_REF(select_cb);
+      }
+      select_cb_list = &API_SELECT_CB_VAR_REF(select_cb);
 #if !LWIP_TCPIP_CORE_LOCKING
-    /* Increasing this counter tells select_check_waiters that the list has changed. */
-    select_cb_ctr++;
+      /* Increasing this counter tells select_check_waiters that the list has changed. */
+      select_cb_ctr++;
 #endif
 
-    /* Now we can safely unprotect */
-    LWIP_SOCKET_SELECT_UNPROTECT(lev2);
+      /* Now we can safely unprotect */
+      LWIP_SOCKET_SELECT_UNPROTECT(lev2);
 
-    /* Increase select_waiting for each socket we are interested in */
-    maxfdp2 = maxfdp1;
-    for (i = LWIP_SOCKET_OFFSET; i < maxfdp1; i++) {
-      if ((readset && FD_ISSET(i, readset)) ||
-          (writeset && FD_ISSET(i, writeset)) ||
-          (exceptset && FD_ISSET(i, exceptset))) {
-        struct lwip_sock *sock;
-        SYS_ARCH_PROTECT(lev);
-        sock = tryget_socket_unconn(i);
-        if (sock != NULL) {
-          sock->select_waiting++;
-          if (sock->select_waiting == 0) {
-            /* overflow - too many threads waiting */
-            sock->select_waiting--;
+      /* Increase select_waiting for each socket we are interested in */
+      maxfdp2 = maxfdp1;
+      for (i = LWIP_SOCKET_OFFSET; i < maxfdp1; i++) {
+        if ((readset && FD_ISSET(i, readset)) ||
+            (writeset && FD_ISSET(i, writeset)) ||
+            (exceptset && FD_ISSET(i, exceptset))) {
+          struct lwip_sock *sock;
+          SYS_ARCH_PROTECT(lev);
+          sock = tryget_socket_unconn(i);
+          if (sock != NULL) {
+            sock->select_waiting++;
+            if (sock->select_waiting == 0) {
+              /* overflow - too many threads waiting */
+              sock->select_waiting--;
+              done_socket(sock);
+              nready = -1;
+              maxfdp2 = i;
+              SYS_ARCH_UNPROTECT(lev);
+              set_errno(EBUSY);
+              break;
+            }
             done_socket(sock);
+          } else {
+            /* Not a valid socket */
             nready = -1;
             maxfdp2 = i;
             SYS_ARCH_UNPROTECT(lev);
-            set_errno(EBUSY);
+            set_errno(EBADF);
             break;
           }
-          done_socket(sock);
-        } else {
-          /* Not a valid socket */
-          nready = -1;
-          maxfdp2 = i;
           SYS_ARCH_UNPROTECT(lev);
-          set_errno(EBADF);
-          break;
         }
-        SYS_ARCH_UNPROTECT(lev);
       }
-    }
 
-    if (nready >= 0) {
-      /* Call lwip_selscan again: there could have been events between
-         the last scan (without us on the list) and putting us on the list! */
-      nready = lwip_selscan(maxfdp1, readset, writeset, exceptset, &lreadset, &lwriteset, &lexceptset);
-      if (!nready) {
-        /* Still none ready, just wait to be woken */
-        if (timeout == 0) {
-          /* Wait forever */
-          msectimeout = 0;
-        } else {
-          long msecs_long = ((timeout->tv_sec * 1000) + ((timeout->tv_usec + 500)/1000));
-          if (msecs_long <= 0) {
-            /* Wait 1ms at least (0 means wait forever) */
-            msectimeout = 1;
+      if (nready >= 0) {
+        /* Call lwip_selscan again: there could have been events between
+           the last scan (without us on the list) and putting us on the list! */
+        nready = lwip_selscan(maxfdp1, readset, writeset, exceptset, &lreadset, &lwriteset, &lexceptset);
+        if (!nready) {
+          /* Still none ready, just wait to be woken */
+          if (timeout == 0) {
+            /* Wait forever */
+            msectimeout = 0;
           } else {
-            msectimeout = (u32_t)msecs_long;
+            long msecs_long = ((timeout->tv_sec * 1000) + ((timeout->tv_usec + 500)/1000));
+            if (msecs_long <= 0) {
+              /* Wait 1ms at least (0 means wait forever) */
+              msectimeout = 1;
+            } else {
+              msectimeout = (u32_t)msecs_long;
+            }
           }
-        }
 
-        waitres = sys_arch_sem_wait(SELECT_SEM_PTR(API_SELECT_CB_VAR_REF(select_cb).sem), msectimeout);
+          waitres = sys_arch_sem_wait(SELECT_SEM_PTR(API_SELECT_CB_VAR_REF(select_cb).sem), msectimeout);
 #if LWIP_NETCONN_SEM_PER_THREAD
-        waited = 1;
+          waited = 1;
 #endif
-      }
-    }
-
-    /* Decrease select_waiting for each socket we are interested in */
-    for (i = LWIP_SOCKET_OFFSET; i < maxfdp2; i++) {
-      if ((readset && FD_ISSET(i, readset)) ||
-          (writeset && FD_ISSET(i, writeset)) ||
-          (exceptset && FD_ISSET(i, exceptset))) {
-        struct lwip_sock *sock;
-        SYS_ARCH_PROTECT(lev);
-        sock = tryget_socket_unconn(i);
-        if (sock != NULL) {
-          /* for now, handle select_waiting==0... */
-          LWIP_ASSERT("sock->select_waiting > 0", sock->select_waiting > 0);
-          if (sock->select_waiting > 0) {
-            sock->select_waiting--;
-          }
-          done_socket(sock);
-        } else {
-          /* Not a valid socket */
-          nready = -1;
-          set_errno(EBADF);
         }
-        SYS_ARCH_UNPROTECT(lev);
       }
-    }
-    /* Take us off the list */
-    LWIP_SOCKET_SELECT_PROTECT(lev2);
-    if (API_SELECT_CB_VAR_REF(select_cb).next != NULL) {
-      API_SELECT_CB_VAR_REF(select_cb).next->prev = API_SELECT_CB_VAR_REF(select_cb).prev;
-    }
-    if (select_cb_list == &API_SELECT_CB_VAR_REF(select_cb)) {
-      LWIP_ASSERT("select_cb.prev == NULL", API_SELECT_CB_VAR_REF(select_cb).prev == NULL);
-      select_cb_list = API_SELECT_CB_VAR_REF(select_cb).next;
-    } else {
-      LWIP_ASSERT("select_cb.prev != NULL", API_SELECT_CB_VAR_REF(select_cb).prev != NULL);
-      API_SELECT_CB_VAR_REF(select_cb).prev->next = API_SELECT_CB_VAR_REF(select_cb).next;
-    }
+
+      /* Decrease select_waiting for each socket we are interested in */
+      for (i = LWIP_SOCKET_OFFSET; i < maxfdp2; i++) {
+        if ((readset && FD_ISSET(i, readset)) ||
+            (writeset && FD_ISSET(i, writeset)) ||
+            (exceptset && FD_ISSET(i, exceptset))) {
+          struct lwip_sock *sock;
+          SYS_ARCH_PROTECT(lev);
+          sock = tryget_socket_unconn(i);
+          if (sock != NULL) {
+            /* for now, handle select_waiting==0... */
+            LWIP_ASSERT("sock->select_waiting > 0", sock->select_waiting > 0);
+            if (sock->select_waiting > 0) {
+              sock->select_waiting--;
+            }
+            done_socket(sock);
+          } else {
+            /* Not a valid socket */
+            nready = -1;
+            set_errno(EBADF);
+          }
+          SYS_ARCH_UNPROTECT(lev);
+        }
+      }
+      /* Take us off the list */
+      LWIP_SOCKET_SELECT_PROTECT(lev2);
+      if (API_SELECT_CB_VAR_REF(select_cb).next != NULL) {
+        API_SELECT_CB_VAR_REF(select_cb).next->prev = API_SELECT_CB_VAR_REF(select_cb).prev;
+      }
+      if (select_cb_list == &API_SELECT_CB_VAR_REF(select_cb)) {
+        LWIP_ASSERT("select_cb.prev == NULL", API_SELECT_CB_VAR_REF(select_cb).prev == NULL);
+        select_cb_list = API_SELECT_CB_VAR_REF(select_cb).next;
+      } else {
+        LWIP_ASSERT("select_cb.prev != NULL", API_SELECT_CB_VAR_REF(select_cb).prev != NULL);
+        API_SELECT_CB_VAR_REF(select_cb).prev->next = API_SELECT_CB_VAR_REF(select_cb).next;
+      }
 #if !LWIP_TCPIP_CORE_LOCKING
-    /* Increasing this counter tells select_check_waiters that the list has changed. */
-    select_cb_ctr++;
+      /* Increasing this counter tells select_check_waiters that the list has changed. */
+      select_cb_ctr++;
 #endif
-    LWIP_SOCKET_SELECT_UNPROTECT(lev2);
+      LWIP_SOCKET_SELECT_UNPROTECT(lev2);
 
 #if LWIP_NETCONN_SEM_PER_THREAD
-    if (API_SELECT_CB_VAR_REF(select_cb).sem_signalled && (!waited || (waitres == SYS_ARCH_TIMEOUT))) {
-      /* don't leave the thread-local semaphore signalled */
-      sys_arch_sem_wait(API_SELECT_CB_VAR_REF(select_cb).sem, 1);
-    }
+      if (API_SELECT_CB_VAR_REF(select_cb).sem_signalled && (!waited || (waitres == SYS_ARCH_TIMEOUT))) {
+        /* don't leave the thread-local semaphore signalled */
+        sys_arch_sem_wait(API_SELECT_CB_VAR_REF(select_cb).sem, 1);
+      }
 #else /* LWIP_NETCONN_SEM_PER_THREAD */
-    sys_sem_free(&API_SELECT_CB_VAR_REF(select_cb).sem);
+      sys_sem_free(&API_SELECT_CB_VAR_REF(select_cb).sem);
 #endif /* LWIP_NETCONN_SEM_PER_THREAD */
-
-    if (nready < 0) {
-      /* This happens when a socket got closed while waiting */
-      lwip_select_dec_sockets_used(maxfdp1, &used_sockets);
       API_SELECT_CB_VAR_FREE(select_cb);
-      return -1;
-    }
 
-    if (waitres == SYS_ARCH_TIMEOUT) {
-      /* Timeout */
-      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_select: timeout expired\n"));
-      /* This is OK as the local fdsets are empty and nready is zero,
-         or we would have returned earlier. */
-      goto return_copy_fdsets;
-    }
+      if (nready < 0) {
+        /* This happens when a socket got closed while waiting */
+        lwip_select_dec_sockets_used(maxfdp1, &used_sockets);
+        API_SELECT_CB_VAR_FREE(select_cb);
+        return -1;
+      }
 
-    /* See what's set */
-    nready = lwip_selscan(maxfdp1, readset, writeset, exceptset, &lreadset, &lwriteset, &lexceptset);
+      if (waitres == SYS_ARCH_TIMEOUT) {
+        /* Timeout */
+        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_select: timeout expired\n"));
+        /* This is OK as the local fdsets are empty and nready is zero,
+           or we would have returned earlier. */
+      } else {
+        /* See what's set now after waiting */
+        nready = lwip_selscan(maxfdp1, readset, writeset, exceptset, &lreadset, &lwriteset, &lexceptset);
+        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_select: nready=%d\n", nready));
+      }
+    }
   }
 
-  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_select: nready=%d\n", nready));
-return_copy_fdsets:
   lwip_select_dec_sockets_used(maxfdp1, &used_sockets);
   set_errno(0);
   if (readset) {
@@ -2073,7 +2071,6 @@ return_copy_fdsets:
   if (exceptset) {
     *exceptset = lexceptset;
   }
-  API_SELECT_CB_VAR_FREE(select_cb);
   return nready;
 }