diff --git a/src/Environment/environment_ctrl.cxx b/src/Environment/environment_ctrl.cxx
index a947c48a9..87b79544a 100644
--- a/src/Environment/environment_ctrl.cxx
+++ b/src/Environment/environment_ctrl.cxx
@@ -330,7 +330,7 @@ FGMetarEnvironmentCtrl::FGMetarEnvironmentCtrl ()
       _dt( 0.0 ),
       _error_dt( 0.0 )
 {
-#if defined(ENABLE_THREADS) && ENABLE_THREADS
+#if defined(ENABLE_THREADS)
     thread = new MetarThread(this);
     thread->start( 1 );
 #endif // ENABLE_THREADS
@@ -338,7 +338,7 @@ FGMetarEnvironmentCtrl::FGMetarEnvironmentCtrl ()
 
 FGMetarEnvironmentCtrl::~FGMetarEnvironmentCtrl ()
 {
-#if defined(ENABLE_THREADS) && ENABLE_THREADS
+#if defined(ENABLE_THREADS)
    thread->cancel();
    thread->join();
 #endif // ENABLE_THREADS
@@ -491,7 +491,7 @@ FGMetarEnvironmentCtrl::update(double delta_time_sec)
         }
     }
 
-#if defined(ENABLE_THREADS) && ENABLE_THREADS
+#if !defined(ENABLE_THREADS)
     // No loader thread running so manually fetch the data
     string id = "";
     while ( !request_queue.empty() ) {
@@ -582,7 +582,7 @@ FGMetarEnvironmentCtrl::fetch_data( const string &icao )
     } catch (const sg_io_exception& e) {
         SG_LOG( SG_GENERAL, SG_WARN, "Error fetching live weather data: "
                 << e.getFormattedMessage().c_str() );
-#if defined(ENABLE_THREADS) && ENABLE_THREADS
+#if defined(ENABLE_THREADS)
         if (_error_count++ >= 3) {
            SG_LOG( SG_GENERAL, SG_WARN, "Stop fetching data permanently.");
            thread->cancel();
@@ -701,7 +701,7 @@ FGMetarEnvironmentCtrl::update_metar_properties( const FGMetar *m )
 }
 
 
-#if defined(ENABLE_THREADS) && ENABLE_THREADS
+#if defined(ENABLE_THREADS)
 /**
  *
  */
diff --git a/src/Environment/environment_ctrl.hxx b/src/Environment/environment_ctrl.hxx
index be009962e..c38e033fc 100644
--- a/src/Environment/environment_ctrl.hxx
+++ b/src/Environment/environment_ctrl.hxx
@@ -27,7 +27,7 @@
 #include <simgear/structure/subsystem_mgr.hxx>
 #include <simgear/environment/metar.hxx>
 
-#if defined(ENABLE_THREADS) && ENABLE_THREADS
+#if defined(ENABLE_THREADS)
 # include <simgear/threads/SGThread.hxx>
 # include <simgear/threads/SGQueue.hxx>
 #endif
@@ -185,7 +185,7 @@ private:
 
 private:
 
-#if defined(ENABLE_THREADS) && ENABLE_THREADS
+#if defined(ENABLE_THREADS)
     /**
      * FIFO queue which holds a pointer to the fetched metar data.
      */
@@ -207,7 +207,7 @@ private:
     queue < FGMetarResult > result_queue;
 #endif
 
-#if defined(ENABLE_THREADS) && ENABLE_THREADS
+#if defined(ENABLE_THREADS)
     /**
      * This class represents the thread of execution responsible for
      * fetching the metar data.
diff --git a/src/Scenery/FGTileLoader.cxx b/src/Scenery/FGTileLoader.cxx
index 03cb493d5..ca61e8294 100644
--- a/src/Scenery/FGTileLoader.cxx
+++ b/src/Scenery/FGTileLoader.cxx
@@ -41,7 +41,7 @@ extern ssgBranch *ground;
  */
 FGTileLoader::FGTileLoader()
 {
-#if defined(ENABLE_THREADS) && ENABLE_THREADS
+#if defined(ENABLE_THREADS)
     // Create and start the loader threads.
     for (int i = 0; i < MAX_THREADS; ++i)
     {
@@ -56,7 +56,7 @@ FGTileLoader::FGTileLoader()
  */
 FGTileLoader::~FGTileLoader()
 {
-#if defined(ENABLE_THREADS) && ENABLE_THREADS
+#if defined(ENABLE_THREADS)
     // Wake up its time to die.
     // queue_cond.broadcast();
 
@@ -121,7 +121,7 @@ void
 FGTileLoader::update()
 {
 
-#if defined(ENABLE_THREADS) && ENABLE_THREADS
+#if defined(ENABLE_THREADS)
     // send a signal to the pager thread that it is allowed to load
     // another tile
     mutex.lock();
@@ -155,7 +155,7 @@ FGTileLoader::update()
 }
 
 
-#if defined(ENABLE_THREADS) && ENABLE_THREADS
+#if defined(ENABLE_THREADS)
 /**
  * 
  */
diff --git a/src/Scenery/FGTileLoader.hxx b/src/Scenery/FGTileLoader.hxx
index 3d912fa75..ef32ec4a0 100644
--- a/src/Scenery/FGTileLoader.hxx
+++ b/src/Scenery/FGTileLoader.hxx
@@ -27,7 +27,7 @@
 #include <simgear/bucket/newbucket.hxx>
 #include <simgear/misc/sg_path.hxx>
 
-#if defined(ENABLE_THREADS) && ENABLE_THREADS
+#if defined(ENABLE_THREADS)
 #  include <simgear/threads/SGThread.hxx>
 #  include <simgear/threads/SGQueue.hxx>
 #else
@@ -97,7 +97,7 @@ private:
 
 private:
 
-#if defined(ENABLE_THREADS) && ENABLE_THREADS
+#if defined(ENABLE_THREADS)
     /**
      * FIFO queue of tiles to load from data files.
      */
@@ -113,7 +113,7 @@ private:
      */
     string_list tile_path;
 
-#if defined(ENABLE_THREADS) && ENABLE_THREADS
+#if defined(ENABLE_THREADS)
     /**
      * Maximum number of threads to create for loading tiles.
      */
diff --git a/src/Scenery/tilemgr.cxx b/src/Scenery/tilemgr.cxx
index af7195b44..353be612d 100644
--- a/src/Scenery/tilemgr.cxx
+++ b/src/Scenery/tilemgr.cxx
@@ -47,7 +47,7 @@
 
 #define TEST_LAST_HIT_CACHE
 
-#if defined(ENABLE_THREADS) && ENABLE_THREADS
+#if defined(ENABLE_THREADS)
 SGLockedQueue<FGTileEntry *> FGTileMgr::attach_queue;
 SGLockedQueue<FGDeferredModel *> FGTileMgr::model_queue;
 #else
@@ -92,7 +92,7 @@ int FGTileMgr::init() {
     }
 
     while ( ! model_queue.empty() ) {
-#if defined(ENABLE_THREADS) && ENABLE_THREADS
+#if defined(ENABLE_THREADS)
         FGDeferredModel* dm = model_queue.pop();
 #else
         FGDeferredModel* dm = model_queue.front();
@@ -299,7 +299,7 @@ void FGTileMgr::update_queues()
 
             // cout << "loading next model ..." << endl;
             // load the next tile in the queue
-#if defined(ENABLE_THREADS) && ENABLE_THREADS
+#if defined(ENABLE_THREADS)
             FGDeferredModel* dm = model_queue.pop();
 #else
             FGDeferredModel* dm = model_queue.front();
@@ -337,7 +337,7 @@ void FGTileMgr::update_queues()
     loader.update();
 
     if ( !attach_queue.empty() ) {
-#if defined(ENABLE_THREADS) && ENABLE_THREADS
+#if defined(ENABLE_THREADS)
         FGTileEntry* e = attach_queue.pop();
 #else
         FGTileEntry* e = attach_queue.front();
@@ -364,7 +364,7 @@ void FGTileMgr::update_queues()
                 // get real serious and agressively free up some tiles so
                 // we don't explode our memory usage.
 
-                SG_LOG( SG_TERRAIN, SG_WARN,
+                SG_LOG( SG_TERRAIN, SG_ALERT,
                         "Warning: catching up on tile delete queue" );
             }
 
diff --git a/src/Scenery/tilemgr.hxx b/src/Scenery/tilemgr.hxx
index 18af47d94..9d41d788c 100644
--- a/src/Scenery/tilemgr.hxx
+++ b/src/Scenery/tilemgr.hxx
@@ -36,7 +36,7 @@
 #include <queue>
 
 #include <simgear/bucket/newbucket.hxx>
-#if defined(ENABLE_THREADS) && ENABLE_THREADS
+#if defined(ENABLE_THREADS)
 #  include <simgear/threads/SGQueue.hxx>
 #endif // ENABLE_THREADS
 
@@ -118,7 +118,7 @@ private:
      * model_queue is the set of models that need to be loaded by the
      * primary render thread.
      */
-#if defined(ENABLE_THREADS) && ENABLE_THREADS
+#if defined(ENABLE_THREADS)
     static SGLockedQueue<FGTileEntry *> attach_queue;
     static SGLockedQueue<FGDeferredModel *> model_queue;
 #else