diff --git a/src/main/java/tconstruct/tools/items/Bowstring.java b/src/main/java/tconstruct/tools/items/Bowstring.java
index eb2d6e98..edbcf99a 100644
--- a/src/main/java/tconstruct/tools/items/Bowstring.java
+++ b/src/main/java/tconstruct/tools/items/Bowstring.java
@@ -40,6 +40,8 @@ public class Bowstring extends CraftingItem implements IToolPart
     @Override
     public int getMaterialID (ItemStack stack)
     {
+        if(stack.getItemDamage() >= toolMaterialNames.length)
+            return -1;
         return stack.getItemDamage();
     }
 
diff --git a/src/main/java/tconstruct/tools/items/Fletching.java b/src/main/java/tconstruct/tools/items/Fletching.java
index 3da80322..5e71f4cb 100644
--- a/src/main/java/tconstruct/tools/items/Fletching.java
+++ b/src/main/java/tconstruct/tools/items/Fletching.java
@@ -34,6 +34,8 @@ public class Fletching extends CraftingItem implements IToolPart
     @Override
     public int getMaterialID (ItemStack stack)
     {
+        if(stack.getItemDamage() >= toolMaterialNames.length)
+            return -1;
         return stack.getItemDamage();
     }
 }
diff --git a/src/main/java/tconstruct/tools/items/ToolPart.java b/src/main/java/tconstruct/tools/items/ToolPart.java
index 7c02b78b..a10495c6 100644
--- a/src/main/java/tconstruct/tools/items/ToolPart.java
+++ b/src/main/java/tconstruct/tools/items/ToolPart.java
@@ -81,6 +81,8 @@ public class ToolPart extends CraftingItem implements IToolPart
     @Override
     public int getMaterialID (ItemStack stack)
     {
+        if(stack.getItemDamage() >= toolMaterialNames.length)
+            return -1;
         return stack.getItemDamage();
     }
 }