diff --git a/src/backend/mmap.c b/src/backend/mmap.c
index dc98ea559..0ff0c8d61 100644
--- a/src/backend/mmap.c
+++ b/src/backend/mmap.c
@@ -193,7 +193,7 @@ lumiera_mmap_init (LumieraMMap self, LumieraFile file, off_t start, size_t size)
   self->address = addr;
   self->refmap = lumiera_calloc ((length-1)/chunksize+1, sizeof (unsigned short));
   self->refcnt = 0;
-  lumiera_mmapcache_announce (lumiera_mcache, self);
+  lumiera_mmapcache_announce (self);
 
   lumiera_file_handle_release (file);
   return self;
@@ -210,7 +210,7 @@ lumiera_mmap_new (LumieraFile file, off_t start, size_t size)
 {
   TRACE (mmap_dbg);
 
-  LumieraMMap self = lumiera_mmapcache_mmap_acquire (lumiera_mcache);
+  LumieraMMap self = lumiera_mmapcache_mmap_acquire ();
 
   if (lumiera_mmap_init (self, file, start, size))
     return self;
@@ -229,7 +229,7 @@ lumiera_mmap_delete (LumieraMMap self)
   if (self)
     {
       REQUIRE (!self->refcnt);
-      lumiera_mmapcache_forget (lumiera_mcache, self);
+      lumiera_mmapcache_forget (self);
 
       /* The matching mappings->lock must be hold or being irrelevant (mappings destructor) here, we can't asset this from here, good luck */
       llist_unlink (&self->searchnode);
@@ -249,9 +249,9 @@ lumiera_mmap_destroy_node (LList node)
   REQUIRE (llist_is_empty (node));
   LumieraMMap self = (LumieraMMap)node;
 
-  lumiera_mmapcache_forget (lumiera_mcache, self);
+  lumiera_mmapcache_forget (self);
 
-  llist_unlink (&self->searchnode); TODO ("must lock mmappings -> deadlock");
+  llist_unlink (&self->searchnode); FIXME ("must lock mmappings -> deadlock");
 
   munmap (self->address, self->size);
   lumiera_free (self->refmap);
diff --git a/src/backend/mmapcache.c b/src/backend/mmapcache.c
index 1f3a79040..cda0493c7 100644
--- a/src/backend/mmapcache.c
+++ b/src/backend/mmapcache.c
@@ -66,19 +66,19 @@ lumiera_mmapcache_delete (void)
 
 
 void*
-lumiera_mmapcache_mmap_acquire (LumieraMMapcache self)
+lumiera_mmapcache_mmap_acquire (void)
 {
   TRACE (mmapcache_dbg);
   void* map = NULL;
 
-  LUMIERA_MUTEX_SECTION (mutex_sync, &self->lock)
+  LUMIERA_MUTEX_SECTION (mutex_sync, &lumiera_mcache->lock)
     {
-      map = lumiera_mrucache_pop (&self->cache);
+      map = lumiera_mrucache_pop (&lumiera_mcache->cache);
     }
 
   if (!map)
     {
-      map = lumiera_malloc (sizeof (*self));
+      map = lumiera_malloc (sizeof (lumiera_mmap));
       TRACE (mmapcache_dbg, "allocated new mmap");
     }
   else
@@ -91,42 +91,42 @@ lumiera_mmapcache_mmap_acquire (LumieraMMapcache self)
 
 
 void
-lumiera_mmapcache_announce (LumieraMMapcache self, LumieraMMap map)
+lumiera_mmapcache_announce (LumieraMMap map)
 {
   TRACE (mmapcache_dbg);
-  LUMIERA_MUTEX_SECTION (mutex_sync, &self->lock)
+  LUMIERA_MUTEX_SECTION (mutex_sync, &lumiera_mcache->lock)
     {
-      self->total += map->size;
+      lumiera_mcache->total += map->size;
     }
 }
 
 
 void
-lumiera_mmapcache_forget (LumieraMMapcache self, LumieraMMap map)
+lumiera_mmapcache_forget (LumieraMMap map)
 {
   TRACE (mmapcache_dbg);
-  LUMIERA_MUTEX_SECTION (mutex_sync, &self->lock)
+  LUMIERA_MUTEX_SECTION (mutex_sync, &lumiera_mcache->lock)
     {
       if (!llist_is_empty (&map->cachenode))
         {
           TODO ("cached stats");
-          REQUIRE (llist_is_member (&self->cache.cache_list, &map->cachenode), "Map object not in cache");
+          REQUIRE (llist_is_member (&lumiera_mcache->cache.cache_list, &map->cachenode), "Map object not in cache");
           llist_unlink (&map->cachenode);
         }
-      self->total -= map->size;
+      lumiera_mcache->total -= map->size;
     }
 }
 
 #if 0
 int
-lumiera_mmapcache_age (LumieraMMapcache self)
+lumiera_mmapcache_age (void)
 {
   TRACE (mmapcache_dbg);
   int ret = 0;
 
-  LUMIERA_MUTEX_SECTION (mmapcache, &self->lock)
+  LUMIERA_MUTEX_SECTION (mmapcache, &lumiera_mcache->lock)
     {
-      ret = lumiera_mrucache_age (&self->cache, 10);      TODO ("age nelem == 20%(configureable) of the cache");
+      ret = lumiera_mrucache_age (&lumiera_mcache->cache, 10);      TODO ("age nelem == 20%(configureable) of the cache");
     }
 
   return ret;
@@ -134,15 +134,15 @@ lumiera_mmapcache_age (LumieraMMapcache self)
 #endif
 
 LumieraMMap
-lumiera_mmapcache_checkout (LumieraMMapcache self, LumieraMMap handle)
+lumiera_mmapcache_checkout (LumieraMMap handle)
 {
   TRACE (mmapcache_dbg);
   REQUIRE (handle->refcnt == 0);
 
-  LUMIERA_MUTEX_SECTION (mutex_sync, &self->lock)
+  LUMIERA_MUTEX_SECTION (mutex_sync, &lumiera_mcache->lock)
     {
       TODO ("cached stats");
-      lumiera_mrucache_checkout (&self->cache, &handle->cachenode);
+      lumiera_mrucache_checkout (&lumiera_mcache->cache, &handle->cachenode);
     }
 
   return handle;
@@ -150,15 +150,15 @@ lumiera_mmapcache_checkout (LumieraMMapcache self, LumieraMMap handle)
 
 
 void
-lumiera_mmapcache_checkin (LumieraMMapcache self, LumieraMMap handle)
+lumiera_mmapcache_checkin (LumieraMMap handle)
 {
   TRACE (mmapcache_dbg);
   REQUIRE (handle->refcnt == 0);
 
-  LUMIERA_MUTEX_SECTION (mutex_sync, &self->lock)
+  LUMIERA_MUTEX_SECTION (mutex_sync, &lumiera_mcache->lock)
     {
       TODO ("cached stats");
-      lumiera_mrucache_checkin (&self->cache, &handle->cachenode);
+      lumiera_mrucache_checkin (&lumiera_mcache->cache, &handle->cachenode);
     }
 }
 
diff --git a/src/backend/mmapcache.h b/src/backend/mmapcache.h
index c6e4a9e86..5b3704512 100644
--- a/src/backend/mmapcache.h
+++ b/src/backend/mmapcache.h
@@ -49,8 +49,6 @@ struct lumiera_mmapcache_struct
   lumiera_mutex lock;
 };
 
-extern LumieraMMapcache lumiera_mcache;
-
 
 /**
  * Initializes the mmapcache.
@@ -71,58 +69,52 @@ lumiera_mmapcache_delete (void);
  * Get a fresh mmap object.
  * when mmaped_limit is reached, the oldest mmap object gets dropped else a new allocated object
  * is returned
- * @param self pointer to the cache
- * @return the new uninitialized mmap
+ * @return the new uninitialized mmap (void* because this is uninitialized)
  */
 void*
-lumiera_mmapcache_mmap_acquire (LumieraMMapcache self);
+lumiera_mmapcache_mmap_acquire (void);
 
 
 /**
  * Announce a new mmap object to the cache quotas.
  * Update the statistics kept in the cache,
  * the map object is still considered to be checked out
- * @param self pointer to the cache
  * @param map object to be announced
  */
 void
-lumiera_mmapcache_announce (LumieraMMapcache self, LumieraMMap map);
+lumiera_mmapcache_announce (LumieraMMap map);
 
 /**
  * Remove a mmap object from the cache quotas.
  * Update the statistics kept in the cache, remove it from the cache.
- * @param self pointer to the cache
  * @param map object to be removed
  */
 void
-lumiera_mmapcache_forget (LumieraMMapcache self, LumieraMMap map);
+lumiera_mmapcache_forget (LumieraMMap map);
 
 /**
  * Destroy and free the nelem oldest elements.
  * Used to free up resources and memory.
- * @param self cache where to free elements.
  * @return nelem-(numer of elements which got freed), that is 0 if all requested elements got freed
  */
 int
-lumiera_mmapcache_age (LumieraMMapcache self);
+lumiera_mmapcache_age (void);
 
 /**
  * Remove a mmap from cache aging
  * Mmaps which are subject of cache aging must be checked out before they can be used.
- * @param self the mmapcache
  * @param handle the mmap to be checked out
  */
 LumieraMMap
-lumiera_mmapcache_checkout (LumieraMMapcache self, LumieraMMap handle);
+lumiera_mmapcache_checkout (LumieraMMap handle);
 
 /**
  * Put a mmap into the cache
  * Mmaps which are checked in are subject of cache aging and might get destroyed and reused.
- * @param self the mmapcache
  * @param handle the mmap to be checked in
  */
 void
-lumiera_mmapcache_checkin (LumieraMMapcache self, LumieraMMap handle);
+lumiera_mmapcache_checkin (LumieraMMap handle);
 
 #endif
 /*
diff --git a/src/backend/mmapings.c b/src/backend/mmapings.c
index 17dbda1e9..b27801b70 100644
--- a/src/backend/mmapings.c
+++ b/src/backend/mmapings.c
@@ -115,7 +115,7 @@ lumiera_mmapings_mmap_acquire (LumieraMMapings self, LumieraFile file, off_t sta
           {
             if (!ret->refcnt)
               /* in cache, needs to me checked out */
-              lumiera_mmapcache_checkout (lumiera_mcache, ret);
+              lumiera_mmapcache_checkout (ret);
           }
         else
           {
@@ -149,7 +149,7 @@ lumiera_mmapings_release_mmap (LumieraMMapings self, LumieraMMap map)
         if (!--map->refcnt)
           {
             TRACE (mmapcache_dbg, "checkin");
-            lumiera_mmapcache_checkin (lumiera_mcache, map);
+            lumiera_mmapcache_checkin (map);
           }
       }
 }