--- a/src/core/ngx_palloc.h
+++ b/src/core/ngx_palloc.h
@@ -19,7 +19,9 @@
  */
 #define NGX_MAX_ALLOC_FROM_POOL  (ngx_pagesize - 1)
 
-#define NGX_DEFAULT_POOL_SIZE   (16 * 1024)
+#define NGX_DEFAULT_POOL_SIZE    (16 * 1024)
+#define NGX_MIN_POOL_SIZE                                                     \
+    (sizeof(ngx_pool_t) + 2 * sizeof(ngx_pool_large_t))
 
 
 typedef void (*ngx_pool_cleanup_pt)(void *data);

--- a/src/http/ngx_http_core_module.c
+++ b/src/http/ngx_http_core_module.c
@@ -70,10 +70,14 @@ static char *ngx_http_core_internal(ngx_
     void *conf);
 
 static char *ngx_http_core_lowat_check(ngx_conf_t *cf, void *post, void *data);
+static char *ngx_http_core_pool_size(ngx_conf_t *cf, void *post, void *data);
 
 static ngx_conf_post_t  ngx_http_core_lowat_post =
     { ngx_http_core_lowat_check };
 
+static ngx_conf_post_handler_pt  ngx_http_core_pool_size_p =
+    ngx_http_core_pool_size;
+
 static ngx_conf_deprecated_t  ngx_conf_deprecated_optimize_host_names = {
     ngx_conf_deprecated, "optimize_host_names", "optimize_server_names"
 };
@@ -129,14 +133,14 @@ static ngx_command_t  ngx_http_core_comm
       ngx_conf_set_size_slot,
       NGX_HTTP_SRV_CONF_OFFSET,
       offsetof(ngx_http_core_srv_conf_t, connection_pool_size),
-      NULL },
+      &ngx_http_core_pool_size_p },
 
     { ngx_string("request_pool_size"),
       NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
       ngx_conf_set_size_slot,
       NGX_HTTP_SRV_CONF_OFFSET,
       offsetof(ngx_http_core_srv_conf_t, request_pool_size),
-      NULL },
+      &ngx_http_core_pool_size_p },
 
     { ngx_string("client_header_timeout"),
       NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
@@ -3052,3 +3056,19 @@ ngx_http_core_lowat_check(ngx_conf_t *cf
 
     return NGX_CONF_OK;
 }
+
+
+static char *
+ngx_http_core_pool_size(ngx_conf_t *cf, void *post, void *data)
+{
+    size_t *sp = data;
+
+    if (*sp < NGX_MIN_POOL_SIZE) {
+        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                           "pool must be no less than %uz", NGX_MIN_POOL_SIZE);
+
+        return NGX_CONF_ERROR;
+    }
+
+    return NGX_CONF_OK;
+}