diff --git a/src/langbot/pkg/utils/image.py b/src/langbot/pkg/utils/image.py
index 5716b07d..0296ba05 100644
--- a/src/langbot/pkg/utils/image.py
+++ b/src/langbot/pkg/utils/image.py
@@ -145,7 +145,8 @@ def get_qq_image_downloadable_url(image_url: str) -> tuple[str, dict]:
     """获取QQ图片的下载链接"""
     parsed = urlparse(image_url)
     query = parse_qs(parsed.query)
-    return f'http://{parsed.netloc}{parsed.path}', query
+    scheme = parsed.scheme or 'http'
+    return f'{scheme}://{parsed.netloc}{parsed.path}', query
 
 
 async def get_qq_image_bytes(image_url: str, query: dict = {}) -> tuple[bytes, str]:
diff --git a/tests/unit_tests/utils/__init__.py b/tests/unit_tests/utils/__init__.py
index e69de29b..8b137891 100644
--- a/tests/unit_tests/utils/__init__.py
+++ b/tests/unit_tests/utils/__init__.py
@@ -0,0 +1 @@
+
diff --git a/tests/unit_tests/utils/test_image.py b/tests/unit_tests/utils/test_image.py
index 0c752a9b..90ab1caf 100644
--- a/tests/unit_tests/utils/test_image.py
+++ b/tests/unit_tests/utils/test_image.py
@@ -56,13 +56,21 @@ class TestGetQQImageDownloadableUrl:
         # Fragment is not included in query string parsing
         assert "http://example.com/image.jpg" in result_url
 
-    def test_https_url(self):
-        """Parse HTTPS URL - note: function returns http:// regardless of input scheme."""
+    def test_https_url_preserves_scheme(self):
+        """Parse HTTPS URL without downgrading the scheme."""
         url = "https://example.com/image.jpg"
         result_url, query = get_qq_image_downloadable_url(url)
 
-        # The function constructs URL with http:// scheme
-        assert "example.com/image.jpg" in result_url
+        assert result_url == "https://example.com/image.jpg"
+        assert query == {}
+
+    def test_missing_scheme_defaults_to_http(self):
+        """Parse scheme-less URL with the existing HTTP default."""
+        url = "example.com/image.jpg?param=value"
+        result_url, query = get_qq_image_downloadable_url(url)
+
+        assert result_url == "http://example.com/image.jpg"
+        assert query == {"param": ["value"]}
 
 
 class TestExtractB64AndFormat: