diff --git a/src/expire-tiles.cpp b/src/expire-tiles.cpp
index 249365070..69ffceda2 100644
--- a/src/expire-tiles.cpp
+++ b/src/expire-tiles.cpp
@@ -114,19 +114,43 @@ void expire_tiles_t::from_polygon_boundary(geom::polygon_t const &geom,
     }
 }
 
+namespace {
+
+template <typename TGEOM>
+expire_mode decide_expire_mode(TGEOM const &geom,
+                               expire_config_t const &expire_config,
+                               geom::box_t *box)
+{
+    if (expire_config.mode != expire_mode::hybrid) {
+        return expire_config.mode;
+    }
+
+    *box = geom::envelope(geom);
+    if (box->width() > expire_config.full_area_limit ||
+        box->height() > expire_config.full_area_limit) {
+        return expire_mode::boundary_only;
+    }
+
+    return expire_mode::full_area;
+}
+
+} // anonymous namespace
+
 void expire_tiles_t::from_geometry(geom::polygon_t const &geom,
                                    expire_config_t const &expire_config)
 {
-    if (expire_config.mode == expire_mode::boundary_only) {
+    geom::box_t box;
+    auto const mode = decide_expire_mode(geom, expire_config, &box);
+
+    if (mode == expire_mode::boundary_only) {
         from_polygon_boundary(geom, expire_config);
         return;
     }
 
-    geom::box_t const box = geom::envelope(geom);
-    if (from_bbox(box, expire_config)) {
-        /* Bounding box too big - just expire tiles on the boundary */
-        from_polygon_boundary(geom, expire_config);
+    if (!box.valid()) {
+        box = geom::envelope(geom);
     }
+    from_bbox(box, expire_config);
 }
 
 void expire_tiles_t::from_polygon_boundary(geom::multipolygon_t const &geom,
@@ -140,16 +164,18 @@ void expire_tiles_t::from_polygon_boundary(geom::multipolygon_t const &geom,
 void expire_tiles_t::from_geometry(geom::multipolygon_t const &geom,
                                    expire_config_t const &expire_config)
 {
-    if (expire_config.mode == expire_mode::boundary_only) {
+    geom::box_t box;
+    auto const mode = decide_expire_mode(geom, expire_config, &box);
+
+    if (mode == expire_mode::boundary_only) {
         from_polygon_boundary(geom, expire_config);
         return;
     }
 
-    geom::box_t const box = geom::envelope(geom);
-    if (from_bbox(box, expire_config)) {
-        /* Bounding box too big - just expire tiles on the boundary */
-        from_polygon_boundary(geom, expire_config);
+    if (!box.valid()) {
+        box = geom::envelope(geom);
     }
+    from_bbox(box, expire_config);
 }
 
 // False positive: Apparently clang-tidy can not see through the visit()
@@ -238,15 +264,6 @@ void expire_tiles_t::from_line_segment(geom::point_t const &a,
 int expire_tiles_t::from_bbox(geom::box_t const &box,
                               expire_config_t const &expire_config)
 {
-    double const width = box.width();
-    double const height = box.height();
-
-    if (expire_config.mode == expire_mode::hybrid &&
-        (width > expire_config.full_area_limit ||
-         height > expire_config.full_area_limit)) {
-        return -1;
-    }
-
     /* Convert the box's Mercator coordinates into tile coordinates */
     auto const tmp_min = coords_to_tile({box.min_x(), box.max_y()});
     int const min_tile_x =
diff --git a/src/geom-box.hpp b/src/geom-box.hpp
index 7bb5f9c76..cd6279ceb 100644
--- a/src/geom-box.hpp
+++ b/src/geom-box.hpp
@@ -72,6 +72,11 @@ class box_t
         return !(a == b);
     }
 
+    bool valid() const noexcept
+    {
+        return m_min_x != std::numeric_limits<double>::max();
+    }
+
 private:
     double m_min_x = std::numeric_limits<double>::max();
     double m_min_y = std::numeric_limits<double>::max();
diff --git a/tests/test-geom-box.cpp b/tests/test-geom-box.cpp
index dec7a96fe..3d1cdd437 100644
--- a/tests/test-geom-box.cpp
+++ b/tests/test-geom-box.cpp
@@ -16,6 +16,7 @@ TEST_CASE("box_t getter/setter", "[NoDB]")
 {
     geom::box_t box{1.0, 2.0, 3.0, 4.0};
 
+    REQUIRE(box.valid());
     REQUIRE(box.min_x() == Approx(1.0));
     REQUIRE(box.max_x() == Approx(3.0));
     REQUIRE(box.min_y() == Approx(2.0));
@@ -57,7 +58,9 @@ TEST_CASE("Extend box_t with points", "[NoDB]")
 {
     geom::box_t box;
 
+    REQUIRE_FALSE(box.valid());
     box.extend(geom::point_t{1.0, 2.0});
+    REQUIRE(box.valid());
 
     REQUIRE(box.min_x() == Approx(1.0));
     REQUIRE(box.max_x() == Approx(1.0));