diff --git a/proxy/proxymanager.go b/proxy/proxymanager.go
index deb017b..5dd8a8d 100644
--- a/proxy/proxymanager.go
+++ b/proxy/proxymanager.go
@@ -374,7 +374,8 @@ func (pm *ProxyManager) proxyOAIHandler(c *gin.Context) {
 
 	// dechunk it as we already have all the body bytes see issue #11
 	c.Request.Header.Del("transfer-encoding")
-	c.Request.Header.Add("content-length", strconv.Itoa(len(bodyBytes)))
+	c.Request.Header.Set("content-length", strconv.Itoa(len(bodyBytes)))
+	c.Request.ContentLength = int64(len(bodyBytes))
 
 	if err := processGroup.ProxyRequest(realModelName, c.Writer, c.Request); err != nil {
 		pm.sendErrorResponse(c, http.StatusInternalServerError, fmt.Sprintf("error proxying request: %s", err.Error()))