diff --git a/Substrate/SubstrateCS/Properties/AssemblyInfo.cs b/Substrate/SubstrateCS/Properties/AssemblyInfo.cs
index 269ca0e..ef4b76e 100644
--- a/Substrate/SubstrateCS/Properties/AssemblyInfo.cs
+++ b/Substrate/SubstrateCS/Properties/AssemblyInfo.cs
@@ -29,5 +29,5 @@ using System.Runtime.InteropServices;
 //      Build Number
 //      Revision
 //
-[assembly: AssemblyVersion("0.5.1.0")]
-[assembly: AssemblyFileVersion("0.5.1.0")]
+[assembly: AssemblyVersion("0.5.2.0")]
+[assembly: AssemblyFileVersion("0.5.2.0")]
diff --git a/Substrate/SubstrateCS/Source/BlockLight.cs b/Substrate/SubstrateCS/Source/BlockLight.cs
index 4f32754..0afd08f 100644
--- a/Substrate/SubstrateCS/Source/BlockLight.cs
+++ b/Substrate/SubstrateCS/Source/BlockLight.cs
@@ -69,13 +69,19 @@ namespace Substrate
             _update.Enqueue(primary);
 
             BlockInfo info = _blockset.GetInfo(lx, ly, lz);
+
             //if (info.Luminance > BlockInfo.MIN_LUMINANCE || info.TransmitsLight) {
-                QueueRelight(new BlockKey(lx - 1, ly, lz));
-                QueueRelight(new BlockKey(lx + 1, ly, lz));
+            if (ly > 0) {
                 QueueRelight(new BlockKey(lx, ly - 1, lz));
+            }
+            if (ly < _ydim - 1) {
                 QueueRelight(new BlockKey(lx, ly + 1, lz));
-                QueueRelight(new BlockKey(lx, ly, lz - 1));
-                QueueRelight(new BlockKey(lx, ly, lz + 1));
+            }
+
+            QueueRelight(new BlockKey(lx - 1, ly, lz));
+            QueueRelight(new BlockKey(lx + 1, ly, lz));
+            QueueRelight(new BlockKey(lx, ly, lz - 1));
+            QueueRelight(new BlockKey(lx, ly, lz + 1));
             //}
 
             UpdateBlockLight();