diff --git a/folium/raster_layers.py b/folium/raster_layers.py
index e76e93a6e8..f8077df8ef 100644
--- a/folium/raster_layers.py
+++ b/folium/raster_layers.py
@@ -214,6 +214,7 @@ def __init__(
         super().__init__(name=name, overlay=overlay, control=control, show=show)
         self.url = url
         kwargs["format"] = fmt
+        cql_filter = kwargs.pop("cql_filter", None)
         self.options = parse_options(
             layers=layers,
             styles=styles,
@@ -222,6 +223,9 @@ def __init__(
             attribution=attr,
             **kwargs
         )
+        if cql_filter:
+            # special parameter that shouldn't be camelized
+            self.options["cql_filter"] = cql_filter
 
 
 class ImageOverlay(Layer):
diff --git a/tests/test_raster_layers.py b/tests/test_raster_layers.py
index c61d4a7be6..1419b30ccf 100644
--- a/tests/test_raster_layers.py
+++ b/tests/test_raster_layers.py
@@ -59,9 +59,14 @@ def test_wms():
         layers="nexrad-n0r-900913",
         attr="Weather data © 2012 IEM Nexrad",
         transparent=True,
+        cql_filter="something",
     )
     w.add_to(m)
-    m._repr_html_()
+    html = m.get_root().render()
+
+    # verify this special case wasn't converted to lowerCamelCase
+    assert '"cql_filter": "something",' in html
+    assert "cqlFilter" not in html
 
     bounds = m.get_bounds()
     assert bounds == [[None, None], [None, None]], bounds