diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9b77fa83a..0ec701cbd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -58,6 +58,7 @@
 * Fixed #1985
 * Fixed a missing texture in the Android Script Editor
 * Fixed #1992
+* Possibly fixed #1951
 
 ## Release Candidate 12 (27 May 2020)
 https://thebusybiscuit.github.io/builds/TheBusyBiscuit/Slimefun4/stable/#12
diff --git a/src/main/java/io/github/thebusybiscuit/slimefun4/implementation/items/electric/machines/ElectricSmeltery.java b/src/main/java/io/github/thebusybiscuit/slimefun4/implementation/items/electric/machines/ElectricSmeltery.java
index 18eec6da5..0d24f71e6 100644
--- a/src/main/java/io/github/thebusybiscuit/slimefun4/implementation/items/electric/machines/ElectricSmeltery.java
+++ b/src/main/java/io/github/thebusybiscuit/slimefun4/implementation/items/electric/machines/ElectricSmeltery.java
@@ -1,8 +1,8 @@
 package io.github.thebusybiscuit.slimefun4.implementation.items.electric.machines;
 
-import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.LinkedList;
 import java.util.List;
 
 import org.bukkit.Material;
@@ -56,12 +56,20 @@ public abstract class ElectricSmeltery extends AContainer {
 
             @Override
             public int[] getSlotsAccessedByItemTransport(DirtyChestMenu menu, ItemTransportFlow flow, ItemStack item) {
-                if (flow == ItemTransportFlow.WITHDRAW) return getOutputSlots();
+                if (flow == ItemTransportFlow.WITHDRAW) {
+                    return getOutputSlots();
+                }
 
-                List<Integer> slots = new ArrayList<>();
+                int fullSlots = 0;
+                List<Integer> slots = new LinkedList<>();
 
                 for (int slot : getInputSlots()) {
-                    if (SlimefunUtils.isItemSimilar(menu.getItemInSlot(slot), item, true)) {
+                    ItemStack stack = menu.getItemInSlot(slot);
+                    if (stack != null && SlimefunUtils.isItemSimilar(stack, item, true)) {
+                        if (stack.getAmount() < stack.getMaxStackSize()) {
+                            fullSlots++;
+                        }
+
                         slots.add(slot);
                     }
                 }
@@ -69,6 +77,10 @@ public abstract class ElectricSmeltery extends AContainer {
                 if (slots.isEmpty()) {
                     return getInputSlots();
                 }
+                else if (fullSlots == slots.size()) {
+                    // All slots with that item are already full
+                    return new int[0];
+                }
                 else {
                     Collections.sort(slots, compareSlots(menu));
                     int[] array = new int[slots.size()];