diff --git a/src/mbgl/text/collision_index.cpp b/src/mbgl/text/collision_index.cpp
index fd284881781..4ffe66b98f0 100644
--- a/src/mbgl/text/collision_index.cpp
+++ b/src/mbgl/text/collision_index.cpp
@@ -26,7 +26,7 @@ static const float viewportPaddingDefault = 100;
 // Viewport padding must be much larger for static tiles to avoid clipped labels.
 static const float viewportPaddingForStaticTiles = 1024;
 
-CollisionIndex::CollisionIndex(const TransformState& transformState_, const MapMode& mapMode)
+CollisionIndex::CollisionIndex(const TransformState& transformState_, MapMode& mapMode)
     : transformState(transformState_),
       viewportPadding(mapMode == MapMode::Tile ? viewportPaddingForStaticTiles : viewportPaddingDefault),
       collisionGrid(transformState.getSize().width + 2 * viewportPadding,
diff --git a/src/mbgl/text/collision_index.hpp b/src/mbgl/text/collision_index.hpp
index abd2c8eef6b..b9e618bd241 100644
--- a/src/mbgl/text/collision_index.hpp
+++ b/src/mbgl/text/collision_index.hpp
@@ -20,7 +20,7 @@ class CollisionIndex {
 public:
     using CollisionGrid = GridIndex<IndexedSubfeature>;
 
-    explicit CollisionIndex(const TransformState&, const MapMode&);
+    explicit CollisionIndex(const TransformState&, MapMode&);
 
     std::pair<bool,bool> placeFeature(const CollisionFeature& feature,
                                       Point<float> shift,