diff --git a/lib/tdeck_ui/UI/LXMF/MapProjection.cpp b/lib/tdeck_ui/UI/LXMF/MapProjection.cpp
index 247a0027..21c5d8ad 100644
--- a/lib/tdeck_ui/UI/LXMF/MapProjection.cpp
+++ b/lib/tdeck_ui/UI/LXMF/MapProjection.cpp
@@ -76,7 +76,13 @@ double normalizeLongitude(double longitude) {
     if (!finite(longitude)) {
         return longitude;
     }
-    return wrap(longitude + 180.0, 360.0) - 180.0;
+    double result = std::fmod(longitude, 360.0);
+    if (result >= 180.0) {
+        result -= 360.0;
+    } else if (result < -180.0) {
+        result += 360.0;
+    }
+    return result;
 }
 
 bool isValidZoom(std::uint32_t zoom) {
@@ -195,10 +201,17 @@ Status viewportTiles(const Viewport& viewport,
         return Status::INVALID_ARGUMENT;
     }
 
+    const double world = worldPixels(zoom);
+    const double clipped_top = viewport.top < 0.0 ? 0.0 : viewport.top;
+    const double clipped_bottom = bottom > world ? world : bottom;
+    if (clipped_top >= clipped_bottom) {
+        return Status::OK;
+    }
+
     double first_x_value = std::floor(viewport.left / tile_size);
     double last_x_value = std::ceil(right / tile_size) - 1.0;
-    double first_y_value = std::floor(viewport.top / tile_size);
-    double last_y_value = std::ceil(bottom / tile_size) - 1.0;
+    double first_y_value = std::floor(clipped_top / tile_size);
+    double last_y_value = std::ceil(clipped_bottom / tile_size) - 1.0;
     if (include_border) {
         first_x_value -= 1.0;
         last_x_value += 1.0;
diff --git a/tests/native/test_map_projection.cpp b/tests/native/test_map_projection.cpp
index 71dcc95e..ce87c21d 100644
--- a/tests/native/test_map_projection.cpp
+++ b/tests/native/test_map_projection.cpp
@@ -60,6 +60,10 @@ void testLongitudeNormalization() {
     CHECK(near(Pyxis::MapProjection::normalizeLongitude(-540.0), -180.0));
     CHECK(near(Pyxis::MapProjection::normalizeLongitude(181.0), -179.0));
     CHECK(near(Pyxis::MapProjection::normalizeLongitude(-181.0), 179.0));
+    const double east_inside = std::nextafter(180.0, -std::numeric_limits<double>::infinity());
+    const double west_outside = std::nextafter(-180.0, -std::numeric_limits<double>::infinity());
+    CHECK(Pyxis::MapProjection::normalizeLongitude(east_inside) == east_inside);
+    CHECK(Pyxis::MapProjection::normalizeLongitude(west_outside) == east_inside);
 }
 
 void testEquatorPrimeMeridian() {
@@ -134,6 +138,19 @@ void testExactViewportEdgesAreExclusive() {
     CHECK(tiles[0].tile.y == 1U);
     CHECK(near(tiles[0].screen_x, 0.0));
     CHECK(near(tiles[0].screen_y, 0.0));
+
+    tiles[0].tile.x = 77U;
+    CHECK(Pyxis::MapProjection::viewportTiles(Viewport{0.0, -256.0, 256U, 256U}, 2U, false, tiles,
+                                               Pyxis::MapProjection::MAX_VIEWPORT_TILES, count) == Status::OK);
+    CHECK(count == 0U);
+    CHECK(tiles[0].tile.x == 77U);
+    CHECK(Pyxis::MapProjection::viewportTiles(Viewport{0.0, 1024.0, 256U, 256U}, 2U, false, tiles,
+                                               Pyxis::MapProjection::MAX_VIEWPORT_TILES, count) == Status::OK);
+    CHECK(count == 0U);
+    CHECK(tiles[0].tile.x == 77U);
+    CHECK(Pyxis::MapProjection::viewportTiles(Viewport{0.0, -1024.0, 256U, 100U}, 2U, true, tiles,
+                                               Pyxis::MapProjection::MAX_VIEWPORT_TILES, count) == Status::OK);
+    CHECK(count == 0U);
 }
 
 void testViewportTwoToThreeTileTransition() {