diff --git a/apps/navmeshtool/worldspacedata.cpp b/apps/navmeshtool/worldspacedata.cpp
index 3de8d2395f..12c8c050a2 100644
--- a/apps/navmeshtool/worldspacedata.cpp
+++ b/apps/navmeshtool/worldspacedata.cpp
@@ -263,17 +263,18 @@ namespace NavMeshTool
 
             const osg::Vec2i cellPosition(cell.mData.mX, cell.mData.mY);
             const std::size_t cellObjectsBegin = data.mObjects.size();
-            const auto cellNameLowerCase
-                = Misc::StringUtils::lowerCase(cell.isExterior() ? ESM::Cell::sDefaultWorldspace : cell.mName);
+            const auto cellWorldspace = Misc::StringUtils::lowerCase(
+                (cell.isExterior() ? ESM::RefId::stringRefId(ESM::Cell::sDefaultWorldspace) : cell.mId)
+                    .serializeText());
             WorldspaceNavMeshInput& navMeshInput = [&]() -> WorldspaceNavMeshInput& {
-                auto it = navMeshInputs.find(cellNameLowerCase);
+                auto it = navMeshInputs.find(cellWorldspace);
                 if (it == navMeshInputs.end())
                 {
                     it = navMeshInputs
-                             .emplace(cellNameLowerCase,
-                                 std::make_unique<WorldspaceNavMeshInput>(cellNameLowerCase, settings.mRecast))
+                             .emplace(cellWorldspace,
+                                 std::make_unique<WorldspaceNavMeshInput>(cellWorldspace, settings.mRecast))
                              .first;
-                    it->second->mTileCachedRecastMeshManager.setWorldspace(cellNameLowerCase, nullptr);
+                    it->second->mTileCachedRecastMeshManager.setWorldspace(cellWorldspace, nullptr);
                 }
                 return *it->second;
             }();
diff --git a/apps/openmw/mwworld/scene.cpp b/apps/openmw/mwworld/scene.cpp
index 313b0ed8f9..92cbd468e9 100644
--- a/apps/openmw/mwworld/scene.cpp
+++ b/apps/openmw/mwworld/scene.cpp
@@ -556,7 +556,7 @@ namespace MWWorld
                                                                   .getExterior(playerCellX, playerCellY)
                                                                   ->getCell()
                                                                   ->getWorldSpace()
-                                                                  .getRefIdString()),
+                                                                  .serializeText()),
             navigatorUpdateGuard.get());
         mNavigator.updateBounds(pos, navigatorUpdateGuard.get());
 
@@ -677,8 +677,8 @@ namespace MWWorld
                 "Testing exterior cells (" + std::to_string(i) + "/" + std::to_string(cells.getExtSize()) + ")...");
 
             CellStore* cell = mWorld.getWorldModel().getExterior(it->mData.mX, it->mData.mY);
-            mNavigator.setWorldspace(
-                Misc::StringUtils::lowerCase(cell->getCell()->getWorldSpace().toString()), navigatorUpdateGuard.get());
+            mNavigator.setWorldspace(Misc::StringUtils::lowerCase(cell->getCell()->getWorldSpace().serializeText()),
+                navigatorUpdateGuard.get());
             const osg::Vec3f position
                 = osg::Vec3f(it->mData.mX + 0.5f, it->mData.mY + 0.5f, 0) * Constants::CellSizeInUnits;
             mNavigator.updateBounds(position, navigatorUpdateGuard.get());
@@ -735,8 +735,8 @@ namespace MWWorld
                 "Testing interior cells (" + std::to_string(i) + "/" + std::to_string(cells.getIntSize()) + ")...");
 
             CellStore* cell = mWorld.getWorldModel().getInterior(it->mName);
-            mNavigator.setWorldspace(
-                Misc::StringUtils::lowerCase(cell->getCell()->getWorldSpace().toString()), navigatorUpdateGuard.get());
+            mNavigator.setWorldspace(Misc::StringUtils::lowerCase(cell->getCell()->getWorldSpace().serializeText()),
+                navigatorUpdateGuard.get());
             ESM::Position position;
             mWorld.findInteriorPosition(it->mName, position);
             mNavigator.updateBounds(position.asVec3(), navigatorUpdateGuard.get());
@@ -892,7 +892,7 @@ namespace MWWorld
         loadingListener->setProgressRange(cell->count());
 
         mNavigator.setWorldspace(
-            Misc::StringUtils::lowerCase(cell->getCell()->getWorldSpace().toString()), navigatorUpdateGuard.get());
+            Misc::StringUtils::lowerCase(cell->getCell()->getWorldSpace().serializeText()), navigatorUpdateGuard.get());
         mNavigator.updateBounds(position.asVec3(), navigatorUpdateGuard.get());
 
         // Load cell.