diff --git a/CHANGELOG.md b/CHANGELOG.md
index fffbe97d8..af93b1d61 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -39,6 +39,7 @@
 * Fixed an error when the server was shutting down
 * Fixed #2721
 * Fixed #2662
+* Fixed #2728
 
 ## Release Candidate 19 (11 Jan 2021)
 
diff --git a/src/main/java/io/github/thebusybiscuit/slimefun4/implementation/items/magical/KnowledgeFlask.java b/src/main/java/io/github/thebusybiscuit/slimefun4/implementation/items/magical/KnowledgeFlask.java
index 99744102d..1e1a5c3ab 100644
--- a/src/main/java/io/github/thebusybiscuit/slimefun4/implementation/items/magical/KnowledgeFlask.java
+++ b/src/main/java/io/github/thebusybiscuit/slimefun4/implementation/items/magical/KnowledgeFlask.java
@@ -1,5 +1,7 @@
 package io.github.thebusybiscuit.slimefun4.implementation.items.magical;
 
+import javax.annotation.ParametersAreNonnullByDefault;
+
 import org.bukkit.Sound;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.ItemStack;
@@ -22,6 +24,7 @@ import me.mrCookieSlime.Slimefun.api.SlimefunItemStack;
  */
 public class KnowledgeFlask extends SimpleSlimefunItem<ItemUseHandler> {
 
+    @ParametersAreNonnullByDefault
     public KnowledgeFlask(Category category, SlimefunItemStack item, RecipeType recipeType, ItemStack[] recipe, ItemStack recipeOutput) {
         super(category, item, recipeType, recipe, recipeOutput);
     }
@@ -33,7 +36,13 @@ public class KnowledgeFlask extends SimpleSlimefunItem<ItemUseHandler> {
 
             if (p.getLevel() >= 1 && (!e.getClickedBlock().isPresent() || !(e.getClickedBlock().get().getType().isInteractable()))) {
                 p.setLevel(p.getLevel() - 1);
-                p.getInventory().addItem(SlimefunItems.FILLED_FLASK_OF_KNOWLEDGE.clone());
+
+                ItemStack item = SlimefunItems.FILLED_FLASK_OF_KNOWLEDGE.clone();
+
+                if (!p.getInventory().addItem(item).isEmpty()) {
+                    // The Item could not be added, let's drop it to the ground (fixes #2728)
+                    p.getWorld().dropItemNaturally(p.getLocation(), item);
+                }
 
                 p.playSound(p.getLocation(), Sound.ENTITY_EXPERIENCE_ORB_PICKUP, 1F, 0.5F);