diff --git a/router/src/lib.rs b/router/src/lib.rs
index e049db318..d99c17951 100644
--- a/router/src/lib.rs
+++ b/router/src/lib.rs
@@ -526,8 +526,8 @@ struct CompletionStreamResponse {
 
 #[derive(Serialize, ToSchema)]
 struct ChatMessage {
-    role: String,
-    content: String,
+    role: Option<String>,
+    content: Option<String>,
 }
 
 #[derive(Serialize, ToSchema)]
@@ -563,7 +563,7 @@ struct ChatCompletionStreamResponse {
     choices: Vec<ChatCompletionStreamResponseChoice>,
 }
 
-#[derive(Serialize, ToSchema)]
+#[derive(Serialize, ToSchema, PartialEq)]
 #[serde(rename_all(serialize = "snake_case"))]
 pub(crate) enum CompletionFinishReason {
     #[schema(rename = "stop")]
@@ -688,6 +688,14 @@ impl From<StreamResponse> for CompletionStreamResponse {
             .unwrap_or(0);
         let total_tokens = prompt_tokens + completion_tokens;
 
+        let finish_reason = resp
+            .details
+            .map(|x| CompletionFinishReason::from(x.finish_reason));
+
+        let is_stop = finish_reason
+            .as_ref()
+            .is_some_and(|x| x == &CompletionFinishReason::Stop);
+
         CompletionStreamResponse {
             id: "null".to_string(),
             object: "text_completion".to_string(),
@@ -695,11 +703,13 @@ impl From<StreamResponse> for CompletionStreamResponse {
             model: "null".to_string(),
             choices: vec![CompletionResponseStreamChoice {
                 index: 0,
-                text: resp.token.text,
+                text: if is_stop {
+                    "".to_string()
+                } else {
+                    resp.token.text
+                },
                 logprobs: None,
-                finish_reason: resp
-                    .details
-                    .map(|x| CompletionFinishReason::from(x.finish_reason)),
+                finish_reason: finish_reason,
             }],
             usage: Some(UsageInfo {
                 prompt_tokens: prompt_tokens,
@@ -728,8 +738,8 @@ impl From<GenerateResponse> for ChatCompletionResponse {
             choices: vec![ChatCompletionResponseChoice {
                 index: 0,
                 message: ChatMessage {
-                    role: "assistant".to_string(),
-                    content: resp.generated_text,
+                    role: Some("assistant".to_string()),
+                    content: Some(resp.generated_text),
                 },
                 finish_reason: resp
                     .details
@@ -746,6 +756,14 @@ impl From<GenerateResponse> for ChatCompletionResponse {
 
 impl From<StreamResponse> for ChatCompletionStreamResponse {
     fn from(resp: StreamResponse) -> Self {
+        let finish_reason = resp
+            .details
+            .map(|x| CompletionFinishReason::from(x.finish_reason));
+
+        let is_stop = finish_reason
+            .as_ref()
+            .is_some_and(|x| x == &CompletionFinishReason::Stop);
+
         ChatCompletionStreamResponse {
             id: "null".to_string(),
             object: "chat.completion.chunk".to_string(),
@@ -754,12 +772,14 @@ impl From<StreamResponse> for ChatCompletionStreamResponse {
             choices: vec![ChatCompletionStreamResponseChoice {
                 index: 0,
                 delta: ChatMessage {
-                    role: "assistant".to_string(),
-                    content: resp.token.text,
+                    role: if is_stop {
+                        None
+                    } else {
+                        Some("assistant".to_string())
+                    },
+                    content: if is_stop { None } else { Some(resp.token.text) },
                 },
-                finish_reason: resp
-                    .details
-                    .map(|x| CompletionFinishReason::from(x.finish_reason)),
+                finish_reason: finish_reason,
             }],
         }
     }