diff --git a/util/dex/dex.go b/util/dex/dex.go
index dd239d34abcd5..735b7cbb72976 100644
--- a/util/dex/dex.go
+++ b/util/dex/dex.go
@@ -17,6 +17,13 @@ import (
 
 var messageRe = regexp.MustCompile(`<p>(.*)([\s\S]*?)<\/p>`)
 
+func decorateDirector(director func(req *http.Request), target *url.URL) func(req *http.Request) {
+	return func(req *http.Request) {
+		director(req)
+		req.Host = target.Host
+	}
+}
+
 // NewDexHTTPReverseProxy returns a reverse proxy to the Dex server. Dex is assumed to be configured
 // with the external issuer URL muxed to the same path configured in server.go. In other words, if
 // Argo CD API server wants to proxy requests at /api/dex, then the dex config yaml issuer URL should
@@ -25,6 +32,7 @@ func NewDexHTTPReverseProxy(serverAddr string, baseHRef string) func(writer http
 	target, err := url.Parse(serverAddr)
 	errors.CheckError(err)
 	target.Path = baseHRef
+
 	proxy := httputil.NewSingleHostReverseProxy(target)
 	proxy.ModifyResponse = func(resp *http.Response) error {
 		if resp.StatusCode == 500 {
@@ -52,6 +60,7 @@ func NewDexHTTPReverseProxy(serverAddr string, baseHRef string) func(writer http
 		}
 		return nil
 	}
+	proxy.Director = decorateDirector(proxy.Director, target)
 	return func(w http.ResponseWriter, r *http.Request) {
 		proxy.ServeHTTP(w, r)
 	}
diff --git a/util/dex/dex_test.go b/util/dex/dex_test.go
index 114903902bd59..ffe1fa7862878 100644
--- a/util/dex/dex_test.go
+++ b/util/dex/dex_test.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"net/http"
 	"net/http/httptest"
+	"net/url"
 	"strings"
 	"testing"
 
@@ -270,7 +271,9 @@ func Test_GenerateDexConfig(t *testing.T) {
 
 func Test_DexReverseProxy(t *testing.T) {
 	t.Run("Good case", func(t *testing.T) {
+		var host string
 		fakeDex := httptest.NewServer(http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
+			host = req.Host
 			rw.WriteHeader(http.StatusOK)
 		}))
 		defer fakeDex.Close()
@@ -278,10 +281,12 @@ func Test_DexReverseProxy(t *testing.T) {
 		server := httptest.NewServer(http.HandlerFunc(NewDexHTTPReverseProxy(fakeDex.URL, "/")))
 		fmt.Printf("Fake API Server listening on %s\n", server.URL)
 		defer server.Close()
+		target, _ := url.Parse(fakeDex.URL)
 		resp, err := http.Get(server.URL)
 		assert.NotNil(t, resp)
 		assert.NoError(t, err)
 		assert.Equal(t, http.StatusOK, resp.StatusCode)
+		assert.Equal(t, host, target.Host)
 		fmt.Printf("%s\n", resp.Status)
 	})