diff --git a/src/main/java/com/raoulvdberge/refinedstorage/apiimpl/util/ItemStackList.java b/src/main/java/com/raoulvdberge/refinedstorage/apiimpl/util/ItemStackList.java
index 2b80e90c9..2e8c61bcf 100755
--- a/src/main/java/com/raoulvdberge/refinedstorage/apiimpl/util/ItemStackList.java
+++ b/src/main/java/com/raoulvdberge/refinedstorage/apiimpl/util/ItemStackList.java
@@ -22,6 +22,11 @@ public class ItemStackList implements IItemStackList {
 
     @Override
     public void add(ItemStack stack) {
+        if (stack == null) {
+            // What you doing adding nulls?
+            return;
+        }
+
         for (ItemStack otherStack : stacks.get(stack.getItem())) {
             if (API.instance().getComparer().isEqualNoQuantity(otherStack, stack)) {
                 if ((long) otherStack.stackSize + (long) stack.stackSize > Integer.MAX_VALUE) {