diff --git a/relay/adaptor/anthropic/adaptor.go b/relay/adaptor/anthropic/adaptor.go
index 44803de4..8dbb20c0 100644
--- a/relay/adaptor/anthropic/adaptor.go
+++ b/relay/adaptor/anthropic/adaptor.go
@@ -14,6 +14,13 @@ import (
 	"github.com/songquanpeng/one-api/relay/relaymode"
 )
 
+const (
+	// NativeAnthropicEndpoint is the endpoint for native Anthropic API
+	NativeAnthropicEndpoint = "/v1/messages"
+	// ThirdPartyAnthropicEndpoint is the endpoint for third-party providers supporting Anthropic protocol
+	ThirdPartyAnthropicEndpoint = "/anthropic/v1/messages"
+)
+
 type Adaptor struct {
 }
 
@@ -24,13 +31,13 @@ func (a *Adaptor) Init(meta *meta.Meta) {
 func (a *Adaptor) GetRequestURL(meta *meta.Meta) (string, error) {
 	// For native Anthropic API
 	if strings.Contains(meta.BaseURL, "api.anthropic.com") {
-		return fmt.Sprintf("%s/v1/messages", meta.BaseURL), nil
+		return fmt.Sprintf("%s%s", meta.BaseURL, NativeAnthropicEndpoint), nil
 	}
 
 	// For third-party providers supporting Anthropic protocol (like DeepSeek)
 	// They typically expose the endpoint at /anthropic/v1/messages
 	baseURL := strings.TrimSuffix(meta.BaseURL, "/")
-	return fmt.Sprintf("%s/anthropic/v1/messages", baseURL), nil
+	return fmt.Sprintf("%s%s", baseURL, ThirdPartyAnthropicEndpoint), nil
 }
 
 func (a *Adaptor) SetupRequestHeader(c *gin.Context, req *http.Request, meta *meta.Meta) error {
diff --git a/relay/adaptor/anthropic/main.go b/relay/adaptor/anthropic/main.go
index b0d721bb..a52d97d5 100644
--- a/relay/adaptor/anthropic/main.go
+++ b/relay/adaptor/anthropic/main.go
@@ -93,9 +93,15 @@ func ConvertRequest(textRequest model.GeneralOpenAIRequest) *Request {
 		if message.Role == "system" && claudeRequest.System.IsEmpty() {
 			// Create a SystemPrompt from the string content
 			systemPrompt := SystemPrompt{}
-			systemData := []byte(`"` + message.StringContent() + `"`) // Wrap in JSON string quotes
-			_ = systemPrompt.UnmarshalJSON(systemData)
-			claudeRequest.System = systemPrompt
+			systemData, err := json.Marshal(message.StringContent()) // Safely escape string for JSON
+			if err != nil {
+				logger.SysError(fmt.Sprintf("Failed to marshal system prompt: %v", err))
+			} else {
+				if err := systemPrompt.UnmarshalJSON(systemData); err != nil {
+					logger.SysError(fmt.Sprintf("Failed to unmarshal system prompt: %v", err))
+				}
+				claudeRequest.System = systemPrompt
+			}
 			continue
 		}
 		claudeMessage := Message{
diff --git a/relay/controller/anthropic.go b/relay/controller/anthropic.go
index a0c512bc..641eb0f2 100644
--- a/relay/controller/anthropic.go
+++ b/relay/controller/anthropic.go
@@ -142,6 +142,12 @@ func getAnthropicRequestBody(c *gin.Context, anthropicRequest *anthropic.Request
 	return bytes.NewBuffer(jsonData), nil
 }
 
+const (
+	// CHARS_PER_TOKEN represents the rough character-to-token ratio for Anthropic models
+	// This is a conservative estimate: approximately 1 token per 4 characters
+	CHARS_PER_TOKEN = 4
+)
+
 func estimateAnthropicTokens(request *anthropic.Request) int {
 	// Simple token estimation for Anthropic requests
 	// This is a rough estimation, actual implementation might need more sophisticated logic
@@ -150,14 +156,14 @@ func estimateAnthropicTokens(request *anthropic.Request) int {
 	// Count tokens in system prompt
 	if !request.System.IsEmpty() {
 		systemText := request.System.String()
-		totalTokens += len(systemText) / 4 // rough estimate: 1 token per 4 characters
+		totalTokens += len(systemText) / CHARS_PER_TOKEN // rough estimate: 1 token per 4 characters
 	}
 
 	// Count tokens in messages
 	for _, message := range request.Messages {
 		for _, content := range message.Content {
 			if content.Type == "text" {
-				totalTokens += len(content.Text) / 4
+				totalTokens += len(content.Text) / CHARS_PER_TOKEN
 			}
 		}
 	}