diff --git a/core/tilesmanager.cpp b/core/tilesmanager.cpp
index cc19c77c5..4b9a75def 100644
--- a/core/tilesmanager.cpp
+++ b/core/tilesmanager.cpp
@@ -67,7 +67,7 @@ class TilesManager::Private
         int width;
         int height;
         int pageNumber;
-        long totalPixels;
+        qulonglong totalPixels;
         Rotation rotation;
         NormalizedRect visibleRect;
         NormalizedRect requestRect;
@@ -377,7 +377,7 @@ void TilesManager::Private::tilesAt( const NormalizedRect &rect, TileNode &tile,
     }
 }
 
-long TilesManager::totalMemory() const
+qulonglong TilesManager::totalMemory() const
 {
     return 4*d->totalPixels;
 }
diff --git a/core/tilesmanager_p.h b/core/tilesmanager_p.h
index 35c2f73d8..3d8afdd4f 100644
--- a/core/tilesmanager_p.h
+++ b/core/tilesmanager_p.h
@@ -142,7 +142,7 @@ class OKULAR_EXPORT TilesManager
         /**
          * The total memory consumed by the tiles manager
          */
-        long totalMemory() const;
+        qulonglong totalMemory() const;
 
         /**
          * Removes at least @p numberOfBytes bytes worth of tiles (least ranked