diff --git a/internal/runtime/executor/claude_executor.go b/internal/runtime/executor/claude_executor.go
index 1680f6f1..74988bc3 100644
--- a/internal/runtime/executor/claude_executor.go
+++ b/internal/runtime/executor/claude_executor.go
@@ -62,7 +62,7 @@ func (e *ClaudeExecutor) Execute(ctx context.Context, auth *cliproxyauth.Auth, r
 	body = e.injectThinkingConfig(req.Model, body)
 
 	if !strings.HasPrefix(modelForUpstream, "claude-3-5-haiku") {
-		// body, _ = sjson.SetRawBytes(body, "system", []byte(misc.ClaudeCodeInstructions))
+		body = checkSystemInstructions(body)
 	}
 	body = applyPayloadConfig(e.cfg, req.Model, body)
 
@@ -162,7 +162,7 @@ func (e *ClaudeExecutor) ExecuteStream(ctx context.Context, auth *cliproxyauth.A
 	}
 	// Inject thinking config based on model suffix for thinking variants
 	body = e.injectThinkingConfig(req.Model, body)
-	// body, _ = sjson.SetRawBytes(body, "system", []byte(misc.ClaudeCodeInstructions))
+	body = checkSystemInstructions(body)
 	body = applyPayloadConfig(e.cfg, req.Model, body)
 
 	// Extract betas from body and convert to header
@@ -295,7 +295,7 @@ func (e *ClaudeExecutor) CountTokens(ctx context.Context, auth *cliproxyauth.Aut
 	}
 
 	if !strings.HasPrefix(modelForUpstream, "claude-3-5-haiku") {
-		// body, _ = sjson.SetRawBytes(body, "system", []byte(misc.ClaudeCodeInstructions))
+		body = checkSystemInstructions(body)
 	}
 
 	// Extract betas from body and convert to header (for count_tokens too)
@@ -676,3 +676,22 @@ func claudeCreds(a *cliproxyauth.Auth) (apiKey, baseURL string) {
 	}
 	return
 }
+
+func checkSystemInstructions(payload []byte) []byte {
+	system := gjson.GetBytes(payload, "system")
+	claudeCodeInstructions := `[{"type":"text","text":"You are Claude Code, Anthropic's official CLI for Claude.","cache_control":{"type":"ephemeral"}}]`
+	if system.IsArray() {
+		if gjson.GetBytes(payload, "system.0.text").String() != "You are Claude Code, Anthropic's official CLI for Claude." {
+			system.ForEach(func(_, part gjson.Result) bool {
+				if part.Get("type").String() == "text" {
+					claudeCodeInstructions, _ = sjson.SetRaw(claudeCodeInstructions, "-1", part.Raw)
+				}
+				return true
+			})
+			payload, _ = sjson.SetRawBytes(payload, "system", []byte(claudeCodeInstructions))
+		}
+	} else {
+		payload, _ = sjson.SetRawBytes(payload, "system", []byte(claudeCodeInstructions))
+	}
+	return payload
+}