diff --git a/chat/chat.go b/chat/chat.go
index 1280679..4924247 100644
--- a/chat/chat.go
+++ b/chat/chat.go
@@ -63,7 +63,7 @@ func (l *Log[T]) Add(grp int64, item T, isbot bool) {
 func (l *Log[T]) Modelize(p model.Protocol, grp int64, sysp string, isusersystem bool) deepinfra.Model {
 	m := p
 	if sysp != "" && !isusersystem {
-		m.System(model.NewContentText(sysp))
+		m.System(sysp)
 	}
 	l.mu.RLock()
 	defer l.mu.RUnlock()
diff --git a/model/api.go b/model/api.go
index d784e8f..fa35faa 100644
--- a/model/api.go
+++ b/model/api.go
@@ -22,7 +22,7 @@ type Requester interface {
 }
 
 type MessageBuilder[T any] interface {
-	System(prompt ...Content) T
+	System(prompt string) T
 	User(prompt ...Content) T
 	Assistant(prompt ...Content) T
 }
diff --git a/model/genai.go b/model/genai.go
index cc26e4a..1c5c718 100644
--- a/model/genai.go
+++ b/model/genai.go
@@ -166,9 +166,9 @@ func (cs Contents) ToGenAIParts() []GenAIPart {
 	return ps
 }
 
-func (opai *GenAI) System(prompt ...Content) Protocol {
+func (opai *GenAI) System(prompt string) Protocol {
 	opai.SystemInstruction = &GenAIContent{
-		Parts: Contents(prompt).ToGenAIParts(),
+		Parts: []GenAIPart{{Text: prompt}},
 	}
 	return opai
 }
diff --git a/model/ollama.go b/model/ollama.go
index 7eadb4b..afd25fa 100644
--- a/model/ollama.go
+++ b/model/ollama.go
@@ -77,11 +77,11 @@ func (ollm *OLLaMA) OutputRaw() Contents {
 	return Contents{NewContentText(ollm.Message.Content)}
 }
 
-func (ollm *OLLaMA) System(prompt ...Content) Protocol {
+func (ollm *OLLaMA) System(prompt string) Protocol {
 	ollm.Messages = make([]OLLaMAMessage, 1, 8)
 	ollm.Messages[0] = OLLaMAMessage{
 		Role:    "system",
-		Content: prompt[0].Text,
+		Content: prompt,
 	}
 	return ollm
 }
diff --git a/model/openai.go b/model/openai.go
index d94d99c..fc09bc1 100644
--- a/model/openai.go
+++ b/model/openai.go
@@ -115,7 +115,7 @@ func (opai *OpenAI) OutputRaw() Contents {
 	return nil
 }
 
-func (opai *OpenAI) System(prompt ...Content) Protocol {
+func (opai *OpenAI) System(prompt string) Protocol {
 	opai.Messages = make([]OpenAIMessage, 1, 8)
 	raw, err := json.Marshal(&prompt)
 	if err != nil {