diff --git a/include/llmr/text/collision.hpp b/include/llmr/text/collision.hpp
index 364a255a9..ef4899c26 100644
--- a/include/llmr/text/collision.hpp
+++ b/include/llmr/text/collision.hpp
@@ -18,13 +18,14 @@ public:
     float getPlacementScale(const GlyphBoxes &glyphs, float minPlacementScale,
                             float maxPlacementScale, float pad);
     PlacementRange getPlacementRange(const GlyphBoxes &glyphs,
-                                     float placementScale);
+                                     float placementScale, bool horizontal);
     void insert(const GlyphBoxes &glyphs, const CollisionAnchor &anchor,
                 float placementScale, const PlacementRange &placementRange,
                 bool horizontal, float padding);
 
 private:
-    void *tree;
+    void *cTree;
+    void *hTree;
 };
 }
 
diff --git a/src/map/map.cpp b/src/map/map.cpp
index 675e4e679..4b99a2f89 100644
--- a/src/map/map.cpp
+++ b/src/map/map.cpp
@@ -482,6 +482,8 @@ void Map::renderLayers(const std::vector<LayerDescription>& layers, RenderPass p
     } else {
         throw std::runtime_error("unknown render pass");
     }
+
+    glFlush();
 }
 
 template <typename Styles>
diff --git a/src/text/collision.cpp b/src/text/collision.cpp
index 90837fbe6..d1488cb29 100644
--- a/src/text/collision.cpp
+++ b/src/text/collision.cpp
@@ -24,10 +24,11 @@ typedef bgi::rtree<PlacementValue, bgi::rstar<16>> Tree;
 using namespace llmr;
 
 Collision::~Collision() {
-    delete ((Tree *)tree);
+    delete ((Tree *)cTree);
+    delete ((Tree *)hTree);
 }
 
-Collision::Collision() : tree(new Tree()) {
+Collision::Collision() : cTree(new Tree()), hTree(new Tree()) {
     const float m = 4096;
 
     // Hack to prevent cross-tile labels
@@ -125,7 +126,7 @@ PlacementProperty Collision::place(const PlacedGlyphs &placed_glyphs,
     }
 
     // Calculate the range it is safe to rotate all glyphs
-    PlacementRange rotationRange = getPlacementRange(glyphs, scale);
+    PlacementRange rotationRange = getPlacementRange(glyphs, scale, horizontal);
     insert(glyphs, anchor, scale, rotationRange, horizontal, padding);
 
     float zoom = log(scale) / log(2);
@@ -164,7 +165,9 @@ float Collision::getPlacementScale(const GlyphBoxes &glyphs,
                       Point{maxPlacedX, maxPlacedY}};
 
         std::vector<PlacementValue> blocking;
-        ((Tree *)tree)
+        ((Tree *)cTree)
+            ->query(bgi::intersects(query_box), std::back_inserter(blocking));
+        ((Tree *)hTree)
             ->query(bgi::intersects(query_box), std::back_inserter(blocking));
 
         if (blocking.size()) {
@@ -229,7 +232,8 @@ float Collision::getPlacementScale(const GlyphBoxes &glyphs,
 }
 
 PlacementRange Collision::getPlacementRange(const GlyphBoxes &glyphs,
-                                            float placementScale) {
+                                            float placementScale,
+                                            bool horizontal) {
     PlacementRange placementRange = {{2.0f * M_PI, 0}};
 
     for (const GlyphBox &glyph : glyphs) {
@@ -245,9 +249,14 @@ PlacementRange Collision::getPlacementRange(const GlyphBoxes &glyphs,
                       Point{maxPlacedX, maxPlacedY}};
 
         std::vector<PlacementValue> blocking;
-        ((Tree *)tree)
+        ((Tree *)hTree)
             ->query(bgi::intersects(query_box), std::back_inserter(blocking));
 
+        if (horizontal) {
+            ((Tree *)cTree)
+                ->query(bgi::intersects(query_box), std::back_inserter(blocking));
+        }
+
         for (const PlacementValue &value : blocking) {
             const Box &s = std::get<0>(value);
             const PlacementBox &b = std::get<1>(value);
@@ -327,5 +336,9 @@ void Collision::insert(const GlyphBoxes &glyphs, const CollisionAnchor &anchor,
     }
 
     // Bulk-insert all glyph boxes
-    ((Tree *)tree)->insert(result.begin(), result.end());
+    if (horizontal) {
+        ((Tree *)hTree)->insert(result.begin(), result.end());
+    } else {
+        ((Tree *)cTree)->insert(result.begin(), result.end());
+    }
 }