diff --git a/api/app/clients/OpenAIClient.js b/api/app/clients/OpenAIClient.js
index f12b7465eb..4f5e29cac8 100644
--- a/api/app/clients/OpenAIClient.js
+++ b/api/app/clients/OpenAIClient.js
@@ -923,7 +923,9 @@ ${convo}
       this.usage &&
       typeof this.usage === 'object' &&
       'completion_tokens_details' in this.usage &&
-      typeof this.usage.completion_tokens_details === 'object'
+      this.usage.completion_tokens_details &&
+      typeof this.usage.completion_tokens_details === 'object' &&
+      'reasoning_tokens' in this.usage.completion_tokens_details
     ) {
       const outputTokens = Math.abs(
         this.usage.completion_tokens_details.reasoning_tokens - this.usage[this.outputTokensKey],
diff --git a/api/app/clients/specs/OpenAIClient.test.js b/api/app/clients/specs/OpenAIClient.test.js
index 4590398419..413150b7e3 100644
--- a/api/app/clients/specs/OpenAIClient.test.js
+++ b/api/app/clients/specs/OpenAIClient.test.js
@@ -701,4 +701,70 @@ describe('OpenAIClient', () => {
       expect(client.modelOptions.stop).toBeUndefined();
     });
   });
+
+  describe('getStreamUsage', () => {
+    it('should return this.usage when completion_tokens_details is null', () => {
+      const client = new OpenAIClient('test-api-key', defaultOptions);
+      client.usage = {
+        completion_tokens_details: null,
+        prompt_tokens: 10,
+        completion_tokens: 20,
+      };
+      client.inputTokensKey = 'prompt_tokens';
+      client.outputTokensKey = 'completion_tokens';
+
+      const result = client.getStreamUsage();
+
+      expect(result).toEqual(client.usage);
+    });
+
+    it('should return this.usage when completion_tokens_details is missing reasoning_tokens', () => {
+      const client = new OpenAIClient('test-api-key', defaultOptions);
+      client.usage = {
+        completion_tokens_details: {
+          other_tokens: 5,
+        },
+        prompt_tokens: 10,
+        completion_tokens: 20,
+      };
+      client.inputTokensKey = 'prompt_tokens';
+      client.outputTokensKey = 'completion_tokens';
+
+      const result = client.getStreamUsage();
+
+      expect(result).toEqual(client.usage);
+    });
+
+    it('should calculate output tokens correctly when completion_tokens_details is present with reasoning_tokens', () => {
+      const client = new OpenAIClient('test-api-key', defaultOptions);
+      client.usage = {
+        completion_tokens_details: {
+          reasoning_tokens: 30,
+          other_tokens: 5,
+        },
+        prompt_tokens: 10,
+        completion_tokens: 20,
+      };
+      client.inputTokensKey = 'prompt_tokens';
+      client.outputTokensKey = 'completion_tokens';
+
+      const result = client.getStreamUsage();
+
+      expect(result).toEqual({
+        reasoning_tokens: 30,
+        other_tokens: 5,
+        prompt_tokens: 10,
+        completion_tokens: 10, // |30 - 20| = 10
+      });
+    });
+
+    it('should return this.usage when it is undefined', () => {
+      const client = new OpenAIClient('test-api-key', defaultOptions);
+      client.usage = undefined;
+
+      const result = client.getStreamUsage();
+
+      expect(result).toBeUndefined();
+    });
+  });
 });