diff --git a/core/request.go b/core/request.go
index ebb1e64..3260f14 100644
--- a/core/request.go
+++ b/core/request.go
@@ -161,7 +161,13 @@ func (r *RequestAccessor) EventToRequest(req events.APIGatewayProxyRequest) (*ht
 				if queryString != "" {
 					queryString += "&"
 				}
-				queryString += url.QueryEscape(q) + "=" + url.QueryEscape(v)
+				if _, err := url.QueryUnescape(q); err != nil {
+					q = url.QueryEscape(q)
+				}
+				if _, err := url.QueryUnescape(v); err != nil {
+					v = url.QueryEscape(v)
+				}
+				queryString += q + "=" + v
 			}
 		}
 		path += "?" + queryString
@@ -173,7 +179,14 @@ func (r *RequestAccessor) EventToRequest(req events.APIGatewayProxyRequest) (*ht
 			if queryString != "" {
 				queryString += "&"
 			}
-			queryString += url.QueryEscape(q) + "=" + url.QueryEscape(req.QueryStringParameters[q])
+			if _, err := url.QueryUnescape(q); err != nil {
+				q = url.QueryEscape(q)
+			}
+			param := req.QueryStringParameters[q]
+			if _, err := url.QueryUnescape(param); err != nil {
+				param = url.QueryEscape(param)
+			}
+			queryString += q + "=" + param
 		}
 		path += "?" + queryString
 	}
diff --git a/core/request_test.go b/core/request_test.go
index b91563b..a47bf30 100644
--- a/core/request_test.go
+++ b/core/request_test.go
@@ -5,8 +5,10 @@ import (
 	"encoding/base64"
 	"io/ioutil"
 	"math/rand"
+	"net/url"
 	"os"
 	"strings"
+	"time"
 
 	"github.com/aws/aws-lambda-go/events"
 	"github.com/aws/aws-lambda-go/lambdacontext"
@@ -64,14 +66,19 @@ var _ = Describe("RequestAccessor tests", func() {
 			Expect(binaryBody).To(Equal(bodyBytes))
 		})
 
+		now := time.Now().UTC()
+		urlEncodedTimestamp := url.QueryEscape(now.Format(time.RFC3339))
+
 		mqsRequest := getProxyRequest("/hello", "GET")
 		mqsRequest.MultiValueQueryStringParameters = map[string][]string{
-			"hello": {"1"},
-			"world": {"2", "3"},
+			"hello":                                 {"1"},
+			"world":                                 {"2", "3"},
+			url.QueryEscape("urlEncoded:Timestamp"): {urlEncodedTimestamp},
 		}
 		mqsRequest.QueryStringParameters = map[string]string{
-			"hello": "1",
-			"world": "2",
+			"hello":                                 "1",
+			"world":                                 "2",
+			url.QueryEscape("urlEncoded:Timestamp"): urlEncodedTimestamp,
 		}
 		It("Populates multiple value query string correctly", func() {
 			httpReq, err := accessor.EventToRequestWithContext(context.Background(), mqsRequest)
@@ -83,22 +90,28 @@ var _ = Describe("RequestAccessor tests", func() {
 			Expect("GET").To(Equal(httpReq.Method))
 
 			query := httpReq.URL.Query()
-			Expect(2).To(Equal(len(query)))
+			Expect(3).To(Equal(len(query)))
 			Expect(query["hello"]).ToNot(BeNil())
 			Expect(query["world"]).ToNot(BeNil())
+			Expect(query["urlEncoded:Timestamp"]).ToNot(BeNil())
 			Expect(1).To(Equal(len(query["hello"])))
 			Expect(2).To(Equal(len(query["world"])))
+			Expect(1).To(Equal(len(query["urlEncoded:Timestamp"])))
 			Expect("1").To(Equal(query["hello"][0]))
 			Expect("2").To(Equal(query["world"][0]))
 			Expect("3").To(Equal(query["world"][1]))
+			parsedTime, err := time.Parse(time.RFC3339, query["urlEncoded:Timestamp"][0])
+			Expect(err).To(BeNil())
+			Expect(parsedTime).To(BeTemporally("~", now, time.Second))
 		})
 
 		// Support `QueryStringParameters` for backward compatibility.
 		// https://github.com/awslabs/aws-lambda-go-api-proxy/issues/37
 		qsRequest := getProxyRequest("/hello", "GET")
 		qsRequest.QueryStringParameters = map[string]string{
-			"hello": "1",
-			"world": "2",
+			"hello":                                 "1",
+			"world":                                 "2",
+			url.QueryEscape("urlEncoded:Timestamp"): urlEncodedTimestamp,
 		}
 		It("Populates query string correctly", func() {
 			httpReq, err := accessor.EventToRequestWithContext(context.Background(), qsRequest)
@@ -109,13 +122,16 @@ var _ = Describe("RequestAccessor tests", func() {
 			Expect("GET").To(Equal(httpReq.Method))
 
 			query := httpReq.URL.Query()
-			Expect(2).To(Equal(len(query)))
+			Expect(3).To(Equal(len(query)))
 			Expect(query["hello"]).ToNot(BeNil())
 			Expect(query["world"]).ToNot(BeNil())
 			Expect(1).To(Equal(len(query["hello"])))
 			Expect(1).To(Equal(len(query["world"])))
 			Expect("1").To(Equal(query["hello"][0]))
 			Expect("2").To(Equal(query["world"][0]))
+			parsedTime, err := time.Parse(time.RFC3339, query["urlEncoded:Timestamp"][0])
+			Expect(err).To(BeNil())
+			Expect(parsedTime).To(BeTemporally("~", now, time.Second))
 		})
 
 		mvhRequest := getProxyRequest("/hello", "GET")