diff --git a/kong/plugins/request-size-limiting/handler.lua b/kong/plugins/request-size-limiting/handler.lua
index 437e417081f..c29721e379f 100644
--- a/kong/plugins/request-size-limiting/handler.lua
+++ b/kong/plugins/request-size-limiting/handler.lua
@@ -2,16 +2,18 @@
 
 local BasePlugin = require "kong.plugins.base_plugin"
 local responses = require "kong.tools.responses"
-local stringy = require "stringy"
+local strip = require("pl.stringx").strip
+
+local MB = 2^20
 
 local RequestSizeLimitingHandler = BasePlugin:extend()
 
 RequestSizeLimitingHandler.PRIORITY = 950
 
 local function check_size(length, allowed_size, headers)
-  local allowed_bytes_size = allowed_size * 100000
+  local allowed_bytes_size = allowed_size * MB
   if length > allowed_bytes_size then
-    if headers.expect and stringy.strip(headers.expect:lower()) == "100-continue" then
+    if headers.expect and strip(headers.expect:lower()) == "100-continue" then
       return responses.send(417, "Request size limit exceeded")
     else
       return responses.send(413, "Request size limit exceeded")
@@ -26,14 +28,15 @@ end
 function RequestSizeLimitingHandler:access(conf)
   RequestSizeLimitingHandler.super.access(self)
   local headers = ngx.req.get_headers()
-  if headers["content-length"] then
-    check_size(tonumber(headers["content-length"]), conf.allowed_payload_size, headers)
+  local cl = headers["content-length"]
+  if cl then
+    check_size(tonumber(cl), conf.allowed_payload_size, headers)
   else
     -- If the request body is too big, this could consume too much memory (to check)
     ngx.req.read_body()
     local data = ngx.req.get_body_data()
     if data then
-      check_size(string.len(data), conf.allowed_payload_size, headers)
+      check_size(#data, conf.allowed_payload_size, headers)
     end
   end
 end
diff --git a/spec/03-plugins/request-size-limiting/01-access_spec.lua b/spec/03-plugins/request-size-limiting/01-access_spec.lua
index 3e37fb2fa64..e45b8890b3e 100644
--- a/spec/03-plugins/request-size-limiting/01-access_spec.lua
+++ b/spec/03-plugins/request-size-limiting/01-access_spec.lua
@@ -1,5 +1,7 @@
 local helpers = require "spec.helpers"
 
+local TEST_SIZE = 1
+
 describe("Plugin: request-size-limiting (access)", function()
   local client
   setup(function()
@@ -15,7 +17,7 @@ describe("Plugin: request-size-limiting (access)", function()
       name = "request-size-limiting",
       api_id = api.id,
       config = {
-        allowed_payload_size = 10
+        allowed_payload_size = TEST_SIZE
       }
     })
 
@@ -29,7 +31,7 @@ describe("Plugin: request-size-limiting (access)", function()
 
   describe("with Content-Length set", function()
     it("allows request of lower size", function()
-      local body = "foo=test&bar=foobar"
+      local body = string.rep("a", TEST_SIZE * 1000000)
 
       local res = assert(client:request {
         method = "POST",
@@ -44,7 +46,7 @@ describe("Plugin: request-size-limiting (access)", function()
       assert.res_status(200, res)
     end)
     it("blocks request exceeding size limit", function()
-      local body = string.rep("a", 11 * 2^20)
+      local body = string.rep("a", TEST_SIZE * 1000000 + 1)
 
       local res = assert(client:send {
         method = "POST",
@@ -63,7 +65,7 @@ describe("Plugin: request-size-limiting (access)", function()
 
   describe("without Content-Length", function()
     it("allows request of lower size", function()
-      local body = "foo=test&bar=foobar"
+      local body = string.rep("a", TEST_SIZE * 1000000)
 
       local res = assert(client:request {
         method = "POST",
@@ -77,7 +79,7 @@ describe("Plugin: request-size-limiting (access)", function()
       assert.res_status(200, res)
     end)
     it("blocks request exceeding size limit", function()
-      local body = string.rep("a", 11 * 2^20)
+      local body = string.rep("a", TEST_SIZE * 1000000 + 1)
 
       local res = assert(client:send {
         method = "POST",
diff --git a/spec/03-plugins/request-transformer/02-api_spec.lua b/spec/03-plugins/request-transformer/02-api_spec.lua
index a23f099cede..e35b18900a7 100644
--- a/spec/03-plugins/request-transformer/02-api_spec.lua
+++ b/spec/03-plugins/request-transformer/02-api_spec.lua
@@ -1,5 +1,4 @@
 local helpers = require "spec.helpers"
-local cjson = require "cjson"
 
 describe("Plugin: request-transformer (API)", function()
   local admin_client
diff --git a/spec/03-plugins/response-transformer/03-api_spec.lua b/spec/03-plugins/response-transformer/03-api_spec.lua
index fc15a23796b..d873fdb25fa 100644
--- a/spec/03-plugins/response-transformer/03-api_spec.lua
+++ b/spec/03-plugins/response-transformer/03-api_spec.lua
@@ -1,5 +1,4 @@
 local helpers = require "spec.helpers"
-local cjson = require "cjson"
 
 describe("Plugin: response-transformer (API)", function()
   local admin_client