diff --git a/wireless/wapi/src/util.h b/wireless/wapi/src/util.h
index 50de0b6eb..e7c304f7f 100644
--- a/wireless/wapi/src/util.h
+++ b/wireless/wapi/src/util.h
@@ -47,29 +47,74 @@
  * Pre-processor Definitions
  ****************************************************************************/
 
-#define WAPI_IOCTL_STRERROR(cmd) \
-  fprintf( \
-    stderr, "%s:%d:%s():ioctl(%s): %s\n", \
-    __FILE__, __LINE__, __func__, \
-    wapi_ioctl_command_name(cmd), strerror(errno))
+#ifdef DEBUG_WIRELESS_ERROR
+#  ifdef CONFIG_LIBC_STRERROR
+#    define WAPI_IOCTL_STRERROR(cmd) \
+      fprintf( \
+        stderr, "%s:%d:%s():ioctl(%s): %s\n", \
+        __FILE__, __LINE__, __func__, \
+        wapi_ioctl_command_name(cmd), strerror(errno))
 
-#define WAPI_STRERROR(fmt, ...) \
-  fprintf( \
-    stderr, "%s:%d:%s():" fmt ": %s\n", \
-    __FILE__, __LINE__, __func__, \
-    ## __VA_ARGS__, strerror(errno))
+#    define WAPI_STRERROR(fmt, ...) \
+      fprintf( \
+          stderr, "%s:%d:%s():" fmt ": %s\n", \
+        __FILE__, __LINE__, __func__, \
+        ## __VA_ARGS__, strerror(errno))
+#  else
+#    define WAPI_IOCTL_STRERROR(cmd) \
+      fprintf( \
+        stderr, "%s:%d:%s():ioctl(%s): %d\n", \
+        __FILE__, __LINE__, __func__, \
+        wapi_ioctl_command_name(cmd), errno)
 
-#define WAPI_ERROR(fmt, ...) \
-  fprintf( \
-    stderr, "%s:%d:%s(): " fmt , \
-    __FILE__, __LINE__, __func__, ## __VA_ARGS__)
+#    define WAPI_STRERROR(fmt, ...) \
+      fprintf( \
+          stderr, "%s:%d:%s():" fmt ": %d\n", \
+        __FILE__, __LINE__, __func__, \
+        ## __VA_ARGS__, errno)
+#  endif
+
+#  define WAPI_ERROR(fmt, ...) \
+    fprintf( \
+      stderr, "%s:%d:%s(): " fmt , \
+      __FILE__, __LINE__, __func__, ## __VA_ARGS__)
+
+#else
+#  ifdef CONFIG_LIBC_STRERROR
+#    define WAPI_IOCTL_STRERROR(cmd) \
+      fprintf( \
+        stderr, "ioctl(%s): %s\n", \
+        wapi_ioctl_command_name(cmd), strerror(errno))
+
+#    define WAPI_STRERROR(fmt, ...) \
+      fprintf( \
+        stderr, fmt ": %s\n", \
+        ## __VA_ARGS__, strerror(errno))
+#  else
+#    define WAPI_IOCTL_STRERROR(cmd) \
+      fprintf( \
+        stderr, "ioctl(%s): %d\n", \
+        wapi_ioctl_command_name(cmd), errno)
+
+#    define WAPI_STRERROR(fmt, ...) \
+      fprintf( \
+        stderr, fmt ": %d\n", \
+        ## __VA_ARGS__, errno)
+#  endif
+
+#  define WAPI_ERROR(fmt, ...) \
+    fprintf( \
+      stderr, fmt , \
+      ## __VA_ARGS__)
+
+#endif
 
 #define WAPI_VALIDATE_PTR(ptr) \
-  if (!ptr) \
-  { \
-    WAPI_ERROR("Null pointer: %s.\n", #ptr); \
-    return -1; \
-  }
+  if (ptr == NULL) \
+    { \
+      WAPI_ERROR("Null pointer: %p\n", ptr); \
+      return -EINVAL; \
+    }
 
 /****************************************************************************
  *  Public Function Prototypes
diff --git a/wireless/wapi/src/wapi.c b/wireless/wapi/src/wapi.c
index 60f00a3b9..a5f53c2d2 100644
--- a/wireless/wapi/src/wapi.c
+++ b/wireless/wapi/src/wapi.c
@@ -76,6 +76,8 @@ typedef void (*cmd3_t)(int sock, FAR const char *arg1,
 
 static int wapi_str2int(FAR const char *str);
 static double wapi_str2double(FAR const char *str);
+static unsigned int wapi_str2ndx(FAR const char *name, FAR const char **list,
+                                 unsigned int listlen);
 
 static void wapi_show_cmd(int sock, FAR const char *ifname);
 static void wapi_ip_cmd(int sock, FAR const char *ifname,
@@ -196,7 +198,13 @@ static unsigned int wapi_str2ndx(FAR const char *name, FAR const char **list,
         }
     }
 
-  WAPI_ERROR("ERROR: Invalid string: %s\n", name);
+  WAPI_ERROR("ERROR: Invalid option string: %s\n", name);
+  WAPI_ERROR("       Valid options include:\n");
+  for (ndx = 0; ndx < listlen; ndx++)
+    {
+      WAPI_ERROR("       - %s\n", list[ndx]);
+    }
+
   exit(EXIT_FAILURE);
 }