diff --git a/src/main/java/tconstruct/weaponry/WeaponryHandler.java b/src/main/java/tconstruct/weaponry/WeaponryHandler.java
index f8fafe30f73..7238594c6a5 100644
--- a/src/main/java/tconstruct/weaponry/WeaponryHandler.java
+++ b/src/main/java/tconstruct/weaponry/WeaponryHandler.java
@@ -163,6 +163,13 @@ public void onProjectileWeaponCrafted(ToolCraftEvent.NormalTool event)
             bottom = TConstructRegistry.getBowMaterial(tags.getInteger("Accessory"));
             string = (BowstringMaterial) TConstructRegistry.getCustomMaterial(tags.getInteger("Handle"), BowstringMaterial.class);
 
+            // some materials seem to be incompatible
+            if(top == null || bottom == null || string == null)
+            {
+                event.setResult(Event.Result.DENY);
+                return;
+            }
+
             drawSpeed = (int) ((top.drawspeed + bottom.drawspeed) / 2f * string.drawspeedModifier);
             flightSpeed = (top.flightSpeedMax + bottom.flightSpeedMax)/2 * string.flightSpeedModifier;
 
@@ -184,6 +191,13 @@ else if(event.tool instanceof Crossbow)
             top = TConstructRegistry.getBowMaterial(tags.getInteger("Head"));
             string = (BowstringMaterial) TConstructRegistry.getCustomMaterial(tags.getInteger("Accessory"), BowstringMaterial.class);
 
+            // some materials seem to be incompatible
+            if(top == null || string == null)
+            {
+                event.setResult(Event.Result.DENY);
+                return;
+            }
+
             drawSpeed = (int) ((float)top.drawspeed * string.drawspeedModifier);
             flightSpeed = (top.flightSpeedMax * string.flightSpeedModifier);