diff --git a/README.md b/README.md
index 8e5471ba..5fc98ae7 100644
--- a/README.md
+++ b/README.md
@@ -367,6 +367,7 @@ Usage: ./gotestwaf [OPTIONS] --url <URL>
 
 Options:
       --addDebugHeader          Add header "X-GoTestWAF-Test" with a hash of the test information in each request
+      --addContentLength        If present, manually set Content-Length header for requests
       --addHeader string        An HTTP header to add to requests
       --blockConnReset          If present, connection resets will be considered as block
       --blockRegex string       Regex to detect a blocking page with the same HTTP response status code as a not blocked request
diff --git a/cmd/gotestwaf/flags.go b/cmd/gotestwaf/flags.go
index d3564cda..75381727 100644
--- a/cmd/gotestwaf/flags.go
+++ b/cmd/gotestwaf/flags.go
@@ -115,6 +115,7 @@ func parseFlags() (args []string, err error) {
 	flag.String("proxy", "", "Proxy URL to use")
 	flag.String("addHeader", "", "An HTTP header to add to requests")
 	flag.Bool("addDebugHeader", false, "Add header \"X-GoTestWAF-Test\" with a hash of the test information in each request")
+	flag.Bool("addContentLength", false, "If present, manually set Content-Length header for requests")
 
 	// GoHTTP client only settings
 	flag.Int("maxIdleConns", 2, "The maximum number of keep-alive connections (gohttp only)")
diff --git a/internal/config/config.go b/internal/config/config.go
index cc38814b..a971b028 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -22,6 +22,7 @@ type Config struct {
 	Proxy          string `mapstructure:"proxy"`
 	AddHeader      string `mapstructure:"addHeader"`
 	AddDebugHeader bool   `mapstructure:"addDebugHeader"`
+	AddContentLength bool `mapstructure:"addContentLength"`
 
 	// GoHTTP client only settings
 	MaxIdleConns    int  `mapstructure:"maxIdleConns"`
diff --git a/internal/payload/placeholder/htmlform.go b/internal/payload/placeholder/htmlform.go
index 0a428063..8ec9921c 100644
--- a/internal/payload/placeholder/htmlform.go
+++ b/internal/payload/placeholder/htmlform.go
@@ -5,6 +5,7 @@ import (
 	"html/template"
 	"net/http"
 	"net/url"
+	"strconv"
 	"strings"
 
 	"github.com/chromedp/chromedp"
@@ -59,6 +60,10 @@ func (p *HTMLForm) prepareGoHTTPClientRequest(requestURL, payload string, config
 	}
 
 	req.Header.Add("Content-Type", "application/x-www-form-urlencoded")
+	// Manually set Content-Length header if configured
+	if globalConfig != nil && globalConfig.AddContentLength {
+		req.Header.Set("Content-Length", strconv.Itoa(len(payload)))
+	}
 
 	return &types.GoHTTPRequest{Req: req}, nil
 }
diff --git a/internal/payload/placeholder/htmlmultpartform.go b/internal/payload/placeholder/htmlmultpartform.go
index de2993eb..ffa82384 100644
--- a/internal/payload/placeholder/htmlmultpartform.go
+++ b/internal/payload/placeholder/htmlmultpartform.go
@@ -7,6 +7,7 @@ import (
 	"mime/multipart"
 	"net/http"
 	"net/url"
+	"strconv"
 
 	"github.com/chromedp/chromedp"
 	"github.com/wallarm/gotestwaf/internal/scanner/clients/chrome/helpers"
@@ -47,32 +48,39 @@ func (p *HTMLMultipartForm) CreateRequest(requestURL, payload string, config Pla
 }
 
 func (p *HTMLMultipartForm) prepareGoHTTPClientRequest(requestURL, payload string, config PlaceholderConfig) (*types.GoHTTPRequest, error) {
+	body := &bytes.Buffer{}
+	writer := multipart.NewWriter(body)
+
 	randomName, err := RandomHex(Seed)
 	if err != nil {
 		return nil, err
 	}
 
-	body := &bytes.Buffer{}
-	writer := multipart.NewWriter(body)
-
-	fw, err := writer.CreateFormField(randomName)
+	part, err := writer.CreateFormFile(randomName, "file")
 	if err != nil {
 		return nil, err
 	}
 
-	_, err = fw.Write([]byte(payload))
+	_, err = part.Write([]byte(payload))
 	if err != nil {
 		return nil, err
 	}
 
-	writer.Close()
+	err = writer.Close()
+	if err != nil {
+		return nil, err
+	}
 
-	req, err := http.NewRequest(http.MethodPost, requestURL, bytes.NewReader(body.Bytes()))
+	req, err := http.NewRequest(http.MethodPost, requestURL, body)
 	if err != nil {
 		return nil, err
 	}
 
 	req.Header.Add("Content-Type", writer.FormDataContentType())
+	// Manually set Content-Length header if configured
+	if globalConfig != nil && globalConfig.AddContentLength {
+		req.Header.Set("Content-Length", strconv.Itoa(body.Len()))
+	}
 
 	return &types.GoHTTPRequest{Req: req}, nil
 }
diff --git a/internal/payload/placeholder/jsonbody.go b/internal/payload/placeholder/jsonbody.go
index 98fb1d67..974083cd 100644
--- a/internal/payload/placeholder/jsonbody.go
+++ b/internal/payload/placeholder/jsonbody.go
@@ -5,6 +5,7 @@ import (
 	"html/template"
 	"net/http"
 	"net/url"
+	"strconv"
 	"strings"
 
 	"github.com/chromedp/chromedp"
@@ -52,6 +53,10 @@ func (p *JSONBody) prepareGoHTTPClientRequest(requestURL, payload string, config
 	}
 
 	req.Header.Add("Content-Type", "application/json")
+	// Manually set Content-Length header if configured
+	if globalConfig != nil && globalConfig.AddContentLength {
+		req.Header.Set("Content-Length", strconv.Itoa(len(payload)))
+	}
 
 	return &types.GoHTTPRequest{Req: req}, nil
 }
diff --git a/internal/payload/placeholder/jsonrequest.go b/internal/payload/placeholder/jsonrequest.go
index e0127efa..d19ba6d7 100644
--- a/internal/payload/placeholder/jsonrequest.go
+++ b/internal/payload/placeholder/jsonrequest.go
@@ -5,6 +5,7 @@ import (
 	"html/template"
 	"net/http"
 	"net/url"
+	"strconv"
 	"strings"
 
 	"github.com/chromedp/chromedp"
@@ -68,6 +69,10 @@ func (p *JSONRequest) prepareGoHTTPClientRequest(requestURL, payload string, con
 	}
 
 	req.Header.Add("Content-Type", "application/json")
+	// Manually set Content-Length header if configured
+	if globalConfig != nil && globalConfig.AddContentLength {
+		req.Header.Set("Content-Length", strconv.Itoa(len(payload)))
+	}
 
 	return &types.GoHTTPRequest{Req: req}, nil
 }
diff --git a/internal/payload/placeholder/placeholder.go b/internal/payload/placeholder/placeholder.go
index 5f431d02..47451930 100644
--- a/internal/payload/placeholder/placeholder.go
+++ b/internal/payload/placeholder/placeholder.go
@@ -5,6 +5,7 @@ import (
 
 	"github.com/wallarm/gotestwaf/internal/helpers"
 	"github.com/wallarm/gotestwaf/internal/scanner/types"
+	"github.com/wallarm/gotestwaf/internal/config"
 )
 
 const (
@@ -28,6 +29,13 @@ type PlaceholderConfig interface {
 	helpers.Hash
 }
 
+var globalConfig *config.Config
+
+// SetGlobalConfig sets the global configuration for placeholders
+func SetGlobalConfig(cfg *config.Config) {
+	globalConfig = cfg
+}
+
 var Placeholders map[string]Placeholder
 
 var placeholders = []Placeholder{
diff --git a/internal/payload/placeholder/requestbody.go b/internal/payload/placeholder/requestbody.go
index 0f2d3d72..49a7ac89 100644
--- a/internal/payload/placeholder/requestbody.go
+++ b/internal/payload/placeholder/requestbody.go
@@ -5,6 +5,7 @@ import (
 	"html/template"
 	"net/http"
 	"net/url"
+	"strconv"
 	"strings"
 
 	"github.com/wallarm/gotestwaf/internal/scanner/clients/chrome/helpers"
@@ -47,12 +48,16 @@ func (p *RequestBody) CreateRequest(requestURL, payload string, config Placehold
 }
 
 func (p *RequestBody) prepareGoHTTPClientRequest(requestURL, payload string, config PlaceholderConfig) (*types.GoHTTPRequest, error) {
-	// check if we need to set Content-Length manually here
 	req, err := http.NewRequest(http.MethodPost, requestURL, strings.NewReader(payload))
 	if err != nil {
 		return nil, err
 	}
 
+	// Manually set Content-Length header if configured
+	if globalConfig != nil && globalConfig.AddContentLength {
+		req.Header.Set("Content-Length", strconv.Itoa(len(payload)))
+	}
+
 	return &types.GoHTTPRequest{Req: req}, nil
 }
 
diff --git a/internal/payload/placeholder/soapbody.go b/internal/payload/placeholder/soapbody.go
index 1757ca6d..0292f887 100644
--- a/internal/payload/placeholder/soapbody.go
+++ b/internal/payload/placeholder/soapbody.go
@@ -5,6 +5,7 @@ import (
 	"html/template"
 	"net/http"
 	"net/url"
+	"strconv"
 	"strings"
 
 	"github.com/chromedp/chromedp"
@@ -86,6 +87,10 @@ func (p *SOAPBody) prepareGoHTTPClientRequest(requestURL, payload string, config
 
 	req.Header.Add("SOAPAction", `"http://schemas.xmlsoap.org/soap/actor/next"`)
 	req.Header.Add("Content-Type", "text/xml")
+	// Manually set Content-Length header if configured
+	if globalConfig != nil && globalConfig.AddContentLength {
+		req.Header.Set("Content-Length", strconv.Itoa(len(payload)))
+	}
 
 	return &types.GoHTTPRequest{Req: req}, nil
 }
diff --git a/internal/payload/placeholder/xmlbody.go b/internal/payload/placeholder/xmlbody.go
index 35c9e95b..487e024f 100644
--- a/internal/payload/placeholder/xmlbody.go
+++ b/internal/payload/placeholder/xmlbody.go
@@ -5,6 +5,7 @@ import (
 	"html/template"
 	"net/http"
 	"net/url"
+	"strconv"
 	"strings"
 
 	"github.com/chromedp/chromedp"
@@ -52,6 +53,10 @@ func (p *XMLBody) prepareGoHTTPClientRequest(requestURL, payload string, config
 	}
 
 	req.Header.Add("Content-Type", "application/xml")
+	// Manually set Content-Length header if configured
+	if globalConfig != nil && globalConfig.AddContentLength {
+		req.Header.Set("Content-Length", strconv.Itoa(len(payload)))
+	}
 
 	return &types.GoHTTPRequest{Req: req}, nil
 }
diff --git a/internal/scanner/scanner.go b/internal/scanner/scanner.go
index 7b45feb8..8e15865e 100644
--- a/internal/scanner/scanner.go
+++ b/internal/scanner/scanner.go
@@ -126,7 +126,7 @@ func New(
 		return nil, errors.Wrap(err, "couldn't create GraphQL client")
 	}
 
-	return &Scanner{
+	scanner := &Scanner{
 		logger:            logger,
 		cfg:               cfg,
 		db:                db,
@@ -136,7 +136,12 @@ func New(
 		requestTemplates:  requestTemplates,
 		router:            router,
 		enableDebugHeader: enableDebugHeader,
-	}, nil
+	}
+
+	// Set global configuration for placeholders
+	placeholder.SetGlobalConfig(cfg)
+
+	return scanner, nil
 }
 
 func (s *Scanner) CheckIfJavaScriptRequired(ctx context.Context) (bool, error) {