diff --git a/backend/internal/service/account_test_service.go b/backend/internal/service/account_test_service.go
index c17aa3ff..8419c2b4 100644
--- a/backend/internal/service/account_test_service.go
+++ b/backend/internal/service/account_test_service.go
@@ -332,10 +332,7 @@ func (s *AccountTestService) testOpenAIAccountConnection(c *gin.Context, account
 		if err != nil {
 			return s.sendErrorAndEnd(c, fmt.Sprintf("Invalid base URL: %s", err.Error()))
 		}
-		// Remove /chat/completions suffix if present, then add /responses
-		normalizedBaseURL = strings.TrimSuffix(normalizedBaseURL, "/")
-		normalizedBaseURL = strings.TrimSuffix(normalizedBaseURL, "/chat/completions")
-		apiURL = normalizedBaseURL + "/responses"
+		apiURL = strings.TrimSuffix(normalizedBaseURL, "/") + "/responses"
 	} else {
 		return s.sendErrorAndEnd(c, fmt.Sprintf("Unsupported account type: %s", account.Type))
 	}
diff --git a/backend/internal/service/openai_gateway_service.go b/backend/internal/service/openai_gateway_service.go
index 1104a3a5..e86aa2d3 100644
--- a/backend/internal/service/openai_gateway_service.go
+++ b/backend/internal/service/openai_gateway_service.go
@@ -738,9 +738,6 @@ func (s *OpenAIGatewayService) buildUpstreamRequest(ctx context.Context, c *gin.
 			if err != nil {
 				return nil, err
 			}
-			// Remove /chat/completions suffix if present, then add /responses
-			validatedURL = strings.TrimSuffix(validatedURL, "/")
-			validatedURL = strings.TrimSuffix(validatedURL, "/chat/completions")
 			targetURL = validatedURL + "/responses"
 		}
 	default: