diff --git a/chat.go b/chat.go
index 995860c40..6b693da5c 100644
--- a/chat.go
+++ b/chat.go
@@ -93,10 +93,11 @@ type ChatMessagePart struct {
 }
 
 type ChatCompletionMessage struct {
-	Role         string `json:"role"`
-	Content      string `json:"content,omitempty"`
-	Refusal      string `json:"refusal,omitempty"`
-	MultiContent []ChatMessagePart
+	Role             string `json:"role"`
+	Content          string `json:"content,omitempty"`
+	ReasoningContent string `json:"reasoning_content,omitempty"`
+	Refusal          string `json:"refusal,omitempty"`
+	MultiContent     []ChatMessagePart
 
 	// This property isn't in the official documentation, but it's in
 	// the documentation for the official library for python:
@@ -119,41 +120,44 @@ func (m ChatCompletionMessage) MarshalJSON() ([]byte, error) {
 	}
 	if len(m.MultiContent) > 0 {
 		msg := struct {
-			Role         string            `json:"role"`
-			Content      string            `json:"-"`
-			Refusal      string            `json:"refusal,omitempty"`
-			MultiContent []ChatMessagePart `json:"content,omitempty"`
-			Name         string            `json:"name,omitempty"`
-			FunctionCall *FunctionCall     `json:"function_call,omitempty"`
-			ToolCalls    []ToolCall        `json:"tool_calls,omitempty"`
-			ToolCallID   string            `json:"tool_call_id,omitempty"`
+			Role             string            `json:"role"`
+			Content          string            `json:"-"`
+			ReasoningContent string            `json:"reasoning_content,omitempty"`
+			Refusal          string            `json:"refusal,omitempty"`
+			MultiContent     []ChatMessagePart `json:"content,omitempty"`
+			Name             string            `json:"name,omitempty"`
+			FunctionCall     *FunctionCall     `json:"function_call,omitempty"`
+			ToolCalls        []ToolCall        `json:"tool_calls,omitempty"`
+			ToolCallID       string            `json:"tool_call_id,omitempty"`
 		}(m)
 		return json.Marshal(msg)
 	}
 
 	msg := struct {
-		Role         string            `json:"role"`
-		Content      string            `json:"content,omitempty"`
-		Refusal      string            `json:"refusal,omitempty"`
-		MultiContent []ChatMessagePart `json:"-"`
-		Name         string            `json:"name,omitempty"`
-		FunctionCall *FunctionCall     `json:"function_call,omitempty"`
-		ToolCalls    []ToolCall        `json:"tool_calls,omitempty"`
-		ToolCallID   string            `json:"tool_call_id,omitempty"`
+		Role             string            `json:"role"`
+		Content          string            `json:"content,omitempty"`
+		ReasoningContent string            `json:"reasoning_content,omitempty"`
+		Refusal          string            `json:"refusal,omitempty"`
+		MultiContent     []ChatMessagePart `json:"-"`
+		Name             string            `json:"name,omitempty"`
+		FunctionCall     *FunctionCall     `json:"function_call,omitempty"`
+		ToolCalls        []ToolCall        `json:"tool_calls,omitempty"`
+		ToolCallID       string            `json:"tool_call_id,omitempty"`
 	}(m)
 	return json.Marshal(msg)
 }
 
 func (m *ChatCompletionMessage) UnmarshalJSON(bs []byte) error {
 	msg := struct {
-		Role         string `json:"role"`
-		Content      string `json:"content,omitempty"`
-		Refusal      string `json:"refusal,omitempty"`
-		MultiContent []ChatMessagePart
-		Name         string        `json:"name,omitempty"`
-		FunctionCall *FunctionCall `json:"function_call,omitempty"`
-		ToolCalls    []ToolCall    `json:"tool_calls,omitempty"`
-		ToolCallID   string        `json:"tool_call_id,omitempty"`
+		Role             string `json:"role"`
+		Content          string `json:"content,omitempty"`
+		ReasoningContent string `json:"reasoning_content,omitempty"`
+		Refusal          string `json:"refusal,omitempty"`
+		MultiContent     []ChatMessagePart
+		Name             string        `json:"name,omitempty"`
+		FunctionCall     *FunctionCall `json:"function_call,omitempty"`
+		ToolCalls        []ToolCall    `json:"tool_calls,omitempty"`
+		ToolCallID       string        `json:"tool_call_id,omitempty"`
 	}{}
 
 	if err := json.Unmarshal(bs, &msg); err == nil {
@@ -161,14 +165,15 @@ func (m *ChatCompletionMessage) UnmarshalJSON(bs []byte) error {
 		return nil
 	}
 	multiMsg := struct {
-		Role         string `json:"role"`
-		Content      string
-		Refusal      string            `json:"refusal,omitempty"`
-		MultiContent []ChatMessagePart `json:"content"`
-		Name         string            `json:"name,omitempty"`
-		FunctionCall *FunctionCall     `json:"function_call,omitempty"`
-		ToolCalls    []ToolCall        `json:"tool_calls,omitempty"`
-		ToolCallID   string            `json:"tool_call_id,omitempty"`
+		Role             string `json:"role"`
+		Content          string
+		ReasoningContent string            `json:"reasoning_content,omitempty"`
+		Refusal          string            `json:"refusal,omitempty"`
+		MultiContent     []ChatMessagePart `json:"content"`
+		Name             string            `json:"name,omitempty"`
+		FunctionCall     *FunctionCall     `json:"function_call,omitempty"`
+		ToolCalls        []ToolCall        `json:"tool_calls,omitempty"`
+		ToolCallID       string            `json:"tool_call_id,omitempty"`
 	}{}
 	if err := json.Unmarshal(bs, &multiMsg); err != nil {
 		return err
diff --git a/chat_stream.go b/chat_stream.go
index 525b4457a..06af5f928 100644
--- a/chat_stream.go
+++ b/chat_stream.go
@@ -6,11 +6,12 @@ import (
 )
 
 type ChatCompletionStreamChoiceDelta struct {
-	Content      string        `json:"content,omitempty"`
-	Role         string        `json:"role,omitempty"`
-	FunctionCall *FunctionCall `json:"function_call,omitempty"`
-	ToolCalls    []ToolCall    `json:"tool_calls,omitempty"`
-	Refusal      string        `json:"refusal,omitempty"`
+	Content          string        `json:"content,omitempty"`
+	Role             string        `json:"role,omitempty"`
+	FunctionCall     *FunctionCall `json:"function_call,omitempty"`
+	ToolCalls        []ToolCall    `json:"tool_calls,omitempty"`
+	Refusal          string        `json:"refusal,omitempty"`
+	ReasoningContent string        `json:"reasoning_content,omitempty"`
 }
 
 type ChatCompletionStreamChoiceLogprobs struct {
diff --git a/stream_reader.go b/stream_reader.go
index ecfa26807..6faefe0a7 100644
--- a/stream_reader.go
+++ b/stream_reader.go
@@ -6,13 +6,14 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"regexp"
 
 	utils "github.com/sashabaranov/go-openai/internal"
 )
 
 var (
-	headerData  = []byte("data: ")
-	errorPrefix = []byte(`data: {"error":`)
+	headerData  = regexp.MustCompile(`^data:\s*`)
+	errorPrefix = regexp.MustCompile(`^data:\s*{"error":`)
 )
 
 type streamable interface {
@@ -70,12 +71,12 @@ func (stream *streamReader[T]) processLines() ([]byte, error) {
 		}
 
 		noSpaceLine := bytes.TrimSpace(rawLine)
-		if bytes.HasPrefix(noSpaceLine, errorPrefix) {
+		if errorPrefix.Match(noSpaceLine) {
 			hasErrorPrefix = true
 		}
-		if !bytes.HasPrefix(noSpaceLine, headerData) || hasErrorPrefix {
+		if !headerData.Match(noSpaceLine) || hasErrorPrefix {
 			if hasErrorPrefix {
-				noSpaceLine = bytes.TrimPrefix(noSpaceLine, headerData)
+				noSpaceLine = headerData.ReplaceAll(noSpaceLine, nil)
 			}
 			writeErr := stream.errAccumulator.Write(noSpaceLine)
 			if writeErr != nil {
@@ -89,7 +90,7 @@ func (stream *streamReader[T]) processLines() ([]byte, error) {
 			continue
 		}
 
-		noPrefixLine := bytes.TrimPrefix(noSpaceLine, headerData)
+		noPrefixLine := headerData.ReplaceAll(noSpaceLine, nil)
 		if string(noPrefixLine) == "[DONE]" {
 			stream.isFinished = true
 			return nil, io.EOF