diff --git a/src/mceditlib/blocktypes/__init__.py b/src/mceditlib/blocktypes/__init__.py
index 16398cc..ea26d4b 100644
--- a/src/mceditlib/blocktypes/__init__.py
+++ b/src/mceditlib/blocktypes/__init__.py
@@ -230,14 +230,11 @@ class BlockTypeSet(object):
             s = f.read()
             log.info(u"Loading block ID mapping from (%s) %s", len(s), f)
             entries = json.loads(s)
-            self.IDsByState.clear()
             for ID, meta, nameAndState in entries:
                 #internalName, blockState = self._splitInternalName(nameAndState)
 
                 self.IDsByState[nameAndState] = ID, meta
             self.statesByID = {v: k for (k, v) in self.IDsByState.iteritems()}
-            assert "minecraft:air" in self.IDsByState
-            assert (0,0) in self.statesByID
         except EnvironmentError as e:
             log.error(u"Exception while loading block ID mapping from %s: %s", f, e)
             traceback.print_exc()
@@ -335,6 +332,7 @@ class PCBlockTypeSet(BlockTypeSet):
     def __init__(self):
         super(PCBlockTypeSet, self).__init__()
         self.name = "Alpha"
+        self.addIDMappingFromFile("idmapping_raw.json")
         self.addIDMappingFromFile("idmapping.json")
         self.addJsonBlocksFromFile("minecraft_raw.json")
         self.addJsonBlocksFromFile("minecraft.json")
diff --git a/src/mceditlib/blocktypes/idmapping.json b/src/mceditlib/blocktypes/idmapping.json
new file mode 100644
index 0000000..20fa049
--- /dev/null
+++ b/src/mceditlib/blocktypes/idmapping.json
@@ -0,0 +1,5 @@
+[
+[50, 5, "minecraft:torch[facing=up]"],
+[75, 5, "minecraft:unlit_redstone_torch[facing=up]"],
+[76, 5, "minecraft:redstone_torch[facing=up]"]
+]