diff --git a/apps/openmw_test_suite/detournavigator/navmeshtilescache.cpp b/apps/openmw_test_suite/detournavigator/navmeshtilescache.cpp
index 93fc5fbaf..8b1ee230d 100644
--- a/apps/openmw_test_suite/detournavigator/navmeshtilescache.cpp
+++ b/apps/openmw_test_suite/detournavigator/navmeshtilescache.cpp
@@ -55,17 +55,22 @@ namespace
 
     TEST_F(DetourNavigatorNavMeshTilesCacheTest, set_should_return_cached_value)
     {
-        const std::size_t maxSize = 1;
+        const std::size_t navMeshDataSize = 1;
+        const std::size_t navMeshKeySize = 49;
+        const std::size_t maxSize = navMeshDataSize + navMeshKeySize;
         NavMeshTilesCache cache(maxSize);
 
         const auto result = cache.set(mAgentHalfExtents, mTilePosition, mRecastMesh, mOffMeshConnections,
                                       std::move(mNavMeshData));
+        ASSERT_TRUE(result);
         EXPECT_EQ(result.get(), (NavMeshDataRef {mData, 1}));
     }
 
     TEST_F(DetourNavigatorNavMeshTilesCacheTest, set_existing_element_should_throw_exception)
     {
-        const std::size_t maxSize = 2;
+        const std::size_t navMeshDataSize = 1;
+        const std::size_t navMeshKeySize = 49;
+        const std::size_t maxSize = 2 * (navMeshDataSize + navMeshKeySize);
         NavMeshTilesCache cache(maxSize);
         const auto anotherData = reinterpret_cast<unsigned char*>(dtAlloc(1, DT_ALLOC_PERM));
         NavMeshData anotherNavMeshData {anotherData, 1};
@@ -79,7 +84,9 @@ namespace
 
     TEST_F(DetourNavigatorNavMeshTilesCacheTest, get_should_return_cached_value)
     {
-        const std::size_t maxSize = 1;
+        const std::size_t navMeshDataSize = 1;
+        const std::size_t navMeshKeySize = 49;
+        const std::size_t maxSize = navMeshDataSize + navMeshKeySize;
         NavMeshTilesCache cache(maxSize);
 
         cache.set(mAgentHalfExtents, mTilePosition, mRecastMesh, mOffMeshConnections, std::move(mNavMeshData));
@@ -121,7 +128,9 @@ namespace
 
     TEST_F(DetourNavigatorNavMeshTilesCacheTest, set_should_replace_unused_value)
     {
-        const std::size_t maxSize = 1;
+        const std::size_t navMeshDataSize = 1;
+        const std::size_t navMeshKeySize = 117;
+        const std::size_t maxSize = navMeshDataSize + navMeshKeySize;
         NavMeshTilesCache cache(maxSize);
 
         const std::vector<RecastMesh::Water> water {1, RecastMesh::Water {1, btTransform::getIdentity()}};
@@ -139,7 +148,9 @@ namespace
 
     TEST_F(DetourNavigatorNavMeshTilesCacheTest, set_should_not_replace_used_value)
     {
-        const std::size_t maxSize = 1;
+        const std::size_t navMeshDataSize = 1;
+        const std::size_t navMeshKeySize = 49;
+        const std::size_t maxSize = navMeshDataSize + navMeshKeySize;
         NavMeshTilesCache cache(maxSize);
 
         const std::vector<RecastMesh::Water> water {1, RecastMesh::Water {1, btTransform::getIdentity()}};
@@ -155,7 +166,9 @@ namespace
 
     TEST_F(DetourNavigatorNavMeshTilesCacheTest, set_should_replace_unused_least_recently_set_value)
     {
-        const std::size_t maxSize = 2;
+        const std::size_t navMeshDataSize = 1;
+        const std::size_t navMeshKeySize = 117;
+        const std::size_t maxSize = 2 * (navMeshDataSize + navMeshKeySize);
         NavMeshTilesCache cache(maxSize);
 
         const std::vector<RecastMesh::Water> leastRecentlySetWater {1, RecastMesh::Water {1, btTransform::getIdentity()}};
@@ -185,7 +198,9 @@ namespace
 
     TEST_F(DetourNavigatorNavMeshTilesCacheTest, set_should_replace_unused_least_recently_used_value)
     {
-        const std::size_t maxSize = 2;
+        const std::size_t navMeshDataSize = 1;
+        const std::size_t navMeshKeySize = 117;
+        const std::size_t maxSize = 2 * (navMeshDataSize + navMeshKeySize);
         NavMeshTilesCache cache(maxSize);
 
         const std::vector<RecastMesh::Water> leastRecentlyUsedWater {1, RecastMesh::Water {1, btTransform::getIdentity()}};
@@ -227,7 +242,9 @@ namespace
 
     TEST_F(DetourNavigatorNavMeshTilesCacheTest, set_should_not_replace_unused_least_recently_used_value_when_item_does_not_not_fit_cache_max_size)
     {
-        const std::size_t maxSize = 1;
+        const std::size_t navMeshDataSize = 1;
+        const std::size_t navMeshKeySize = 49;
+        const std::size_t maxSize = 2 * (navMeshDataSize + navMeshKeySize);
         NavMeshTilesCache cache(maxSize);
 
         const std::vector<RecastMesh::Water> water {1, RecastMesh::Water {1, btTransform::getIdentity()}};
@@ -243,7 +260,10 @@ namespace
 
     TEST_F(DetourNavigatorNavMeshTilesCacheTest, set_should_not_replace_unused_least_recently_used_value_when_item_does_not_not_fit_size_of_unused_items)
     {
-        const std::size_t maxSize = 2;
+        const std::size_t navMeshDataSize = 1;
+        const std::size_t navMeshKeySize1 = 49;
+        const std::size_t navMeshKeySize2 = 117;
+        const std::size_t maxSize = 2 * navMeshDataSize + navMeshKeySize1 + navMeshKeySize2;
         NavMeshTilesCache cache(maxSize);
 
         const std::vector<RecastMesh::Water> anotherWater {1, RecastMesh::Water {1, btTransform::getIdentity()}};
@@ -269,7 +289,9 @@ namespace
 
     TEST_F(DetourNavigatorNavMeshTilesCacheTest, release_used_after_set_then_used_by_get_item_should_left_this_item_available)
     {
-        const std::size_t maxSize = 1;
+        const std::size_t navMeshDataSize = 1;
+        const std::size_t navMeshKeySize = 49;
+        const std::size_t maxSize = navMeshDataSize + navMeshKeySize;
         NavMeshTilesCache cache(maxSize);
 
         const std::vector<RecastMesh::Water> water {1, RecastMesh::Water {1, btTransform::getIdentity()}};
@@ -290,7 +312,9 @@ namespace
 
     TEST_F(DetourNavigatorNavMeshTilesCacheTest, release_twice_used_item_should_left_this_item_available)
     {
-        const std::size_t maxSize = 1;
+        const std::size_t navMeshDataSize = 1;
+        const std::size_t navMeshKeySize = 49;
+        const std::size_t maxSize = navMeshDataSize + navMeshKeySize;
         NavMeshTilesCache cache(maxSize);
 
         const std::vector<RecastMesh::Water> water {1, RecastMesh::Water {1, btTransform::getIdentity()}};
diff --git a/components/detournavigator/navmeshtilescache.cpp b/components/detournavigator/navmeshtilescache.cpp
index 8c5fc6381..484831493 100644
--- a/components/detournavigator/navmeshtilescache.cpp
+++ b/components/detournavigator/navmeshtilescache.cpp
@@ -1,6 +1,8 @@
 #include "navmeshtilescache.hpp"
 #include "exceptions.hpp"
 
+#include <iostream>
+
 namespace DetourNavigator
 {
     namespace
@@ -61,6 +63,7 @@ namespace DetourNavigator
         if (tileValues == agentValues->second.end())
             return Value();
 
+        // TODO: use different function to make key to avoid unnecessary std::string allocation
         const auto tile = tileValues->second.find(makeNavMeshKey(recastMesh, offMeshConnections));
         if (tile == tileValues->second.end())
             return Value();
@@ -84,11 +87,17 @@ namespace DetourNavigator
         if (navMeshSize > mFreeNavMeshDataSize + (mMaxNavMeshDataSize - mUsedNavMeshDataSize))
             return Value();
 
-        while (!mFreeItems.empty() && mUsedNavMeshDataSize + navMeshSize > mMaxNavMeshDataSize)
+        const auto navMeshKey = makeNavMeshKey(recastMesh, offMeshConnections);
+        const auto itemSize = navMeshSize + navMeshKey.size();
+
+        if (itemSize > mFreeNavMeshDataSize + (mMaxNavMeshDataSize - mUsedNavMeshDataSize))
+            return Value();
+
+        while (!mFreeItems.empty() && mUsedNavMeshDataSize + itemSize > mMaxNavMeshDataSize)
             removeLeastRecentlyUsed();
 
-        const auto navMeshKey = makeNavMeshKey(recastMesh, offMeshConnections);
         const auto iterator = mFreeItems.emplace(mFreeItems.end(), agentHalfExtents, changedTile, navMeshKey);
+        // TODO: use std::string_view or some alternative to avoid navMeshKey copy into both mFreeItems and mValues
         const auto emplaced = mValues[agentHalfExtents][changedTile].emplace(navMeshKey, iterator);
 
         if (!emplaced.second)
@@ -98,8 +107,8 @@ namespace DetourNavigator
         }
 
         iterator->mNavMeshData = std::move(value);
-        mUsedNavMeshDataSize += navMeshSize;
-        mFreeNavMeshDataSize += navMeshSize;
+        mUsedNavMeshDataSize += itemSize;
+        mFreeNavMeshDataSize += itemSize;
 
         acquireItemUnsafe(iterator);
 
@@ -122,7 +131,7 @@ namespace DetourNavigator
         if (value == tileValues->second.end())
             return;
 
-        mUsedNavMeshDataSize -= static_cast<std::size_t>(item.mNavMeshData.mSize);
+        mUsedNavMeshDataSize -= static_cast<std::size_t>(item.mNavMeshData.mSize) + item.mNavMeshKey.size();
         mFreeItems.pop_back();
 
         tileValues->second.erase(value);
@@ -142,7 +151,7 @@ namespace DetourNavigator
             return;
 
         mBusyItems.splice(mBusyItems.end(), mFreeItems, iterator);
-        mFreeNavMeshDataSize -= static_cast<std::size_t>(iterator->mNavMeshData.mSize);
+        mFreeNavMeshDataSize -= static_cast<std::size_t>(iterator->mNavMeshData.mSize) + iterator->mNavMeshKey.size();
     }
 
     void NavMeshTilesCache::releaseItem(ItemIterator iterator)
@@ -153,6 +162,6 @@ namespace DetourNavigator
         const std::lock_guard<std::mutex> lock(mMutex);
 
         mFreeItems.splice(mFreeItems.begin(), mBusyItems, iterator);
-        mFreeNavMeshDataSize += static_cast<std::size_t>(iterator->mNavMeshData.mSize);
+        mFreeNavMeshDataSize += static_cast<std::size_t>(iterator->mNavMeshData.mSize) + iterator->mNavMeshKey.size();
     }
 }