diff --git a/chat.go b/chat.go
index 8b8172ded..2a53c1697 100644
--- a/chat.go
+++ b/chat.go
@@ -121,7 +121,7 @@ type ChatCompletionMessage struct {
 	ToolCallID string `json:"tool_call_id,omitempty"`
 
 	// Messari custom fields
-	Prefix bool `json:"prefix"`
+	Prefix bool `json:"prefix,omitempty"`
 }
 
 func (m ChatCompletionMessage) MarshalJSON() ([]byte, error) {
@@ -139,6 +139,7 @@ func (m ChatCompletionMessage) MarshalJSON() ([]byte, error) {
 			FunctionCall     *FunctionCall     `json:"function_call,omitempty"`
 			ToolCalls        []ToolCall        `json:"tool_calls,omitempty"`
 			ToolCallID       string            `json:"tool_call_id,omitempty"`
+			Prefix           bool              `json:"prefix,omitempty"`
 		}(m)
 		return json.Marshal(msg)
 	}
@@ -153,6 +154,7 @@ func (m ChatCompletionMessage) MarshalJSON() ([]byte, error) {
 		FunctionCall     *FunctionCall     `json:"function_call,omitempty"`
 		ToolCalls        []ToolCall        `json:"tool_calls,omitempty"`
 		ToolCallID       string            `json:"tool_call_id,omitempty"`
+		Prefix           bool              `json:"prefix,omitempty"`
 	}(m)
 	return json.Marshal(msg)
 }
@@ -168,6 +170,7 @@ func (m *ChatCompletionMessage) UnmarshalJSON(bs []byte) error {
 		FunctionCall     *FunctionCall `json:"function_call,omitempty"`
 		ToolCalls        []ToolCall    `json:"tool_calls,omitempty"`
 		ToolCallID       string        `json:"tool_call_id,omitempty"`
+		Prefix           bool          `json:"prefix,omitempty"`
 	}{}
 
 	if err := json.Unmarshal(bs, &msg); err == nil {
@@ -184,6 +187,7 @@ func (m *ChatCompletionMessage) UnmarshalJSON(bs []byte) error {
 		FunctionCall     *FunctionCall     `json:"function_call,omitempty"`
 		ToolCalls        []ToolCall        `json:"tool_calls,omitempty"`
 		ToolCallID       string            `json:"tool_call_id,omitempty"`
+		Prefix           bool              `json:"prefix,omitempty"`
 	}{}
 	if err := json.Unmarshal(bs, &multiMsg); err != nil {
 		return err
diff --git a/messages.go b/messages.go
index 47eb0cd89..538833f54 100644
--- a/messages.go
+++ b/messages.go
@@ -26,7 +26,7 @@ type Message struct {
 	httpHeader
 
 	// Messari custom fields
-	Prefix bool `json:"prefix"`
+	Prefix bool `json:"prefix,omitempty"`
 }
 
 type MessagesList struct {