diff --git a/lib/obj2gltf.js b/lib/obj2gltf.js
index 0d1e2eb..260df96 100644
--- a/lib/obj2gltf.js
+++ b/lib/obj2gltf.js
@@ -15,6 +15,7 @@ var fsExtraOutputJson = Promise.promisify(fsExtra.outputJson);
 var defaultValue = Cesium.defaultValue;
 var defined = Cesium.defined;
 var DeveloperError = Cesium.DeveloperError;
+var RuntimeError = Cesium.RuntimeError;
 
 module.exports = obj2gltf;
 
@@ -85,7 +86,7 @@ function obj2gltf(objPath, gltfPath, options) {
     }
 
     if (binary && bypassPipeline) {
-        throw new DeveloperError('--bypassPipeline does not convert to binary glTF');
+        return Promise.reject(new RuntimeError('--bypassPipeline does not convert to binary glTF'));
     }
 
     gltfPath = path.join(path.dirname(gltfPath), modelName + extension);