diff --git a/MCGalaxy/Blocks/Behaviour/PlaceBehaviour.cs b/MCGalaxy/Blocks/Behaviour/PlaceBehaviour.cs
index 4ce4480b1..6f4fee035 100644
--- a/MCGalaxy/Blocks/Behaviour/PlaceBehaviour.cs
+++ b/MCGalaxy/Blocks/Behaviour/PlaceBehaviour.cs
@@ -52,7 +52,7 @@ namespace MCGalaxy.Blocks {
                 p.ChangeBlock(x, y, z, Block.staircasestep, 0); return;
             }
             
-            p.SendBlockchange(x, y, z, Block.air); // send the air block back only to the user
+            p.SendBlockchange(x, y, z, Block.air, 0); // send the air block back only to the user
             p.ChangeBlock(x, (ushort)(y - 1), z, Block.staircasefull, 0);
         }
         
@@ -62,7 +62,7 @@ namespace MCGalaxy.Blocks {
                 p.ChangeBlock(x, y, z, Block.cobblestoneslab, 0); return;
             }
             
-            p.SendBlockchange(x, y, z, Block.air); // send the air block back only to the user
+            p.SendBlockchange(x, y, z, Block.air, 0); // send the air block back only to the user
             p.ChangeBlock(x, (ushort)(y - 1), z, Block.stone, 0);
         }
         
diff --git a/MCGalaxy/Commands/Fun/WeaponCmd.cs b/MCGalaxy/Commands/Fun/WeaponCmd.cs
index 2194a6dd9..6267e26ab 100644
--- a/MCGalaxy/Commands/Fun/WeaponCmd.cs
+++ b/MCGalaxy/Commands/Fun/WeaponCmd.cs
@@ -105,7 +105,7 @@ namespace MCGalaxy.Commands {
                     foreach (Vec3U16 cP in toSend) {
                         if (lastSent.Contains(cP)) continue;
                         lastSent.Add(cP);
-                        p.SendBlockchange(cP.X, cP.Y, cP.Z, Block.glass);
+                        p.SendBlockchange(cP.X, cP.Y, cP.Z, Block.glass, 0);
                     }
                     toSend.Clear();
                 }
diff --git a/MCGalaxy/Commands/building/CmdMessageBlock.cs b/MCGalaxy/Commands/building/CmdMessageBlock.cs
index 31b4f53ca..6ab99d12a 100644
--- a/MCGalaxy/Commands/building/CmdMessageBlock.cs
+++ b/MCGalaxy/Commands/building/CmdMessageBlock.cs
@@ -173,7 +173,7 @@ namespace MCGalaxy.Commands.Building {
         
         static void ShowMessageBlocks(Player p, DataTable table) {
             foreach (DataRow row in table.Rows) {
-                p.SendBlockchange(U16(row["X"]), U16(row["Y"]), U16(row["Z"]), Block.green);
+                p.SendBlockchange(U16(row["X"]), U16(row["Y"]), U16(row["Z"]), Block.green, 0);
             }
             Player.Message(p, "Now showing &a" + table.Rows.Count + " %SMBs.");
         }
diff --git a/MCGalaxy/Commands/building/CmdPortal.cs b/MCGalaxy/Commands/building/CmdPortal.cs
index b407b73ac..a1e0ff95d 100644
--- a/MCGalaxy/Commands/building/CmdPortal.cs
+++ b/MCGalaxy/Commands/building/CmdPortal.cs
@@ -88,7 +88,7 @@ namespace MCGalaxy.Commands.Building {
             if (data.Multi && type == Block.red && data.Entries.Count > 0) { ExitChange(p, x, y, z, type, extType); return; }
 
             p.level.Blockchange(p, x, y, z, data.Block, data.ExtBlock);
-            p.SendBlockchange(x, y, z, Block.green);
+            p.SendBlockchange(x, y, z, Block.green, 0);
             PortalPos Port;
 
             Port.Map = p.level.name;
@@ -162,8 +162,8 @@ namespace MCGalaxy.Commands.Building {
         static void ShowPortals(Player p, DataTable table) {
             foreach (DataRow row in table.Rows) {
                 if (row["ExitMap"].ToString() == p.level.name)
-                    p.SendBlockchange(U16(row["ExitX"]), U16(row["ExitY"]), U16(row["ExitZ"]), Block.red);
-                p.SendBlockchange(U16(row["EntryX"]), U16(row["EntryY"]), U16(row["EntryZ"]), Block.green);
+                    p.SendBlockchange(U16(row["ExitX"]), U16(row["ExitY"]), U16(row["ExitZ"]), Block.red, 0);
+                p.SendBlockchange(U16(row["EntryX"]), U16(row["EntryY"]), U16(row["EntryZ"]), Block.green, 0);
             }
 
             Player.Message(p, "Now showing &a" + table.Rows.Count + " %Sportals.");
diff --git a/MCGalaxy/Commands/other/CmdFly.cs b/MCGalaxy/Commands/other/CmdFly.cs
index 0cfe4dd1d..ac3d84020 100644
--- a/MCGalaxy/Commands/other/CmdFly.cs
+++ b/MCGalaxy/Commands/other/CmdFly.cs
@@ -46,7 +46,7 @@ namespace MCGalaxy.Commands {
                         DoFly(p, oldpos, last, next);
 
                     foreach (Vec3U16 cP in last)
-                        p.SendBlockchange(cP.X, cP.Y, cP.Z, Block.air);
+                        p.SendBlockchange(cP.X, cP.Y, cP.Z, Block.air, 0);
                     Player.Message(p, "Stopped flying");
                 }));
             flyThread.Name = "MCG_Fly";
@@ -77,14 +77,14 @@ namespace MCGalaxy.Commands {
                 foreach (Vec3U16 P in next) {
                     if (last.Contains(P)) continue;
                     last.Add(P);
-                    p.SendBlockchange(P.X, P.Y, P.Z, Block.glass);
+                    p.SendBlockchange(P.X, P.Y, P.Z, Block.glass, 0);
                 }
                 
                 for (int i = 0; i < last.Count; i++) {
                     Vec3U16 P = last[i];
                     if (next.Contains(P)) continue;
                     
-                    p.SendBlockchange(P.X, P.Y, P.Z, Block.air);
+                    p.SendBlockchange(P.X, P.Y, P.Z, Block.air, 0);
                     last.RemoveAt(i); i--;
                 }
                 next.Clear();
diff --git a/MCGalaxy/Levels/Level.Blocks.cs b/MCGalaxy/Levels/Level.Blocks.cs
index a2d533a86..3455ddfbe 100644
--- a/MCGalaxy/Levels/Level.Blocks.cs
+++ b/MCGalaxy/Levels/Level.Blocks.cs
@@ -90,9 +90,10 @@ namespace MCGalaxy {
             return def == null ? Block.air : def.FallBack;
         }
         
-        public byte GetFallback(byte extType) {
-            BlockDefinition def = CustomBlockDefs[extType];
-            return def == null ? Block.air : def.FallBack;
+        public byte RawFallback(byte raw) {
+            BlockDefinition def = CustomBlockDefs[raw];
+            if (def != null) return def.FallBack;
+            return raw < Block.CpeCount ? raw : Block.air;
         }
         
         public void SetTile(int index, byte block) {
diff --git a/MCGalaxy/Network/Player.Networking.cs b/MCGalaxy/Network/Player.Networking.cs
index 6e824b217..50ca3b65e 100644
--- a/MCGalaxy/Network/Player.Networking.cs
+++ b/MCGalaxy/Network/Player.Networking.cs
@@ -366,29 +366,13 @@ namespace MCGalaxy {
             SendRaw(Opcode.RemoveEntity, id);
         }
         
+        [Obsolete("Prefer SendBlockChange(x, y, z, block, extBlock)")]
         public void SendBlockchange(ushort x, ushort y, ushort z, byte block) {
-            //if (x < 0 || y < 0 || z < 0) return;
-            if (x >= level.Width || y >= level.Height || z >= level.Length) return;
-
-            byte[] buffer = new byte[8];
-            buffer[0] = Opcode.SetBlock;
-            NetUtils.WriteU16(x, buffer, 1);
-            NetUtils.WriteU16(y, buffer, 3);
-            NetUtils.WriteU16(z, buffer, 5);
-            
-            if (block == Block.custom_block) {
-                block = hasBlockDefs ? level.GetExtTile(x, y, z) : level.GetFallbackExtTile(x, y, z);
-            } else {
-                block = Block.Convert(block);
-            }
-            
-            // TODO: custom blocks replacing core blocks
-            if (!hasCustomBlocks) block = Block.ConvertCPE(block);
-            buffer[7] = block;
-            Send(buffer);
+            byte extBlock = 0;
+            if (block == Block.custom_block) extBlock = level.GetExtTile(x, y, z);
+            SendBlockchange(x, y, z, block, extBlock);
         }
         
-        // Duplicated as this packet needs to have maximum optimisation.
         public void SendBlockchange(ushort x, ushort y, ushort z, byte block, byte extBlock) {
             //if (x < 0 || y < 0 || z < 0) return;
             if (x >= level.Width || y >= level.Height || z >= level.Length) return;
@@ -400,12 +384,18 @@ namespace MCGalaxy {
             NetUtils.WriteU16(z, buffer, 5);
             
             if (block == Block.custom_block) {
-                block = hasBlockDefs ? extBlock : level.GetFallback(extBlock);
+                block = hasBlockDefs ? extBlock : level.RawFallback(extBlock);
             } else {
                 block = Block.Convert(block);
             }
-
-            if (!hasCustomBlocks) block = Block.ConvertCPE(block);            
+            if (!hasCustomBlocks) block = Block.ConvertCPE(block); // client doesn't support CPE
+            
+            // Custom block replaced a core block
+            if (!hasBlockDefs && block < Block.CpeCount) {
+                BlockDefinition def = level.CustomBlockDefs[block];
+                if (def != null) block = def.FallBack;
+            }
+            
             buffer[7] = block;
             Send(buffer);
         }
@@ -433,10 +423,9 @@ namespace MCGalaxy {
         public void SendChangeModel(byte id, string model) {
             // Fallback block models for clients that don't support block definitions
             byte block;
-            bool fallback = byte.TryParse(model, out block) && block >= Block.CpeCount;
-            block = level == null ? block : level.GetFallback(block);
-            if (fallback && !hasBlockDefs && block != Block.air)
-                model = block.ToString();
+            if (byte.TryParse(model, out block) && !hasBlockDefs) {
+                model = level.RawFallback(block).ToString();
+            }
 
             Send(Packet.ChangeModel(id, model, hasCP437));
         }
diff --git a/MCGalaxy/Player/Player.CPE.cs b/MCGalaxy/Player/Player.CPE.cs
index d217c6935..1ba578d44 100644
--- a/MCGalaxy/Player/Player.CPE.cs
+++ b/MCGalaxy/Player/Player.CPE.cs
@@ -149,10 +149,8 @@ namespace MCGalaxy {
         string lastUrl = "";
         public void SendCurrentMapAppearance() {
             byte side = (byte)level.EdgeBlock, edge = (byte)level.HorizonBlock;
-            if (side >= Block.CpeCount && !hasBlockDefs)
-                side = level.GetFallback(side);
-            if (edge >= Block.CpeCount && !hasBlockDefs)
-                edge = level.GetFallback(edge);
+            if (!hasBlockDefs) side = level.RawFallback(side);
+            if (!hasBlockDefs) edge = level.RawFallback(edge);
             
             if (HasCpeExt(CpeExt.EnvMapAspect)) {
                 string url = GetTextureUrl();
diff --git a/MCGalaxy/util/IO/BufferedBlockSender.cs b/MCGalaxy/util/IO/BufferedBlockSender.cs
index db83eeef6..fdf658de8 100644
--- a/MCGalaxy/util/IO/BufferedBlockSender.cs
+++ b/MCGalaxy/util/IO/BufferedBlockSender.cs
@@ -144,7 +144,7 @@ namespace MCGalaxy {
                 data[j++] = (byte)(x >> 8); data[j++] = (byte)x;
                 data[j++] = (byte)(y >> 8); data[j++] = (byte)y;
                 data[j++] = (byte)(z >> 8); data[j++] = (byte)z;
-                data[j++] = types[i] < Block.CpeCount ? types[i] : level.GetFallback(types[i]);
+                data[j++] = level.RawFallback(types[i]);
             }
             return data;
         }
@@ -161,8 +161,7 @@ namespace MCGalaxy {
                 data[j++] = (byte)(x >> 8); data[j++] = (byte)x;
                 data[j++] = (byte)(y >> 8); data[j++] = (byte)y;
                 data[j++] = (byte)(z >> 8); data[j++] = (byte)z;
-                data[j++] = types[i] < Block.CpeCount ? Block.ConvertCPE(types[i])
-                    : Block.ConvertCPE(level.GetFallback(types[i]));
+                data[j++] = types[i] = Block.ConvertCPE(level.RawFallback(types[i]));
             }
             return data;
         }