diff --git a/worldedit-bukkit/src/main/java/com/boydti/fawe/bukkit/adapter/mc1_15_2/FAWEWorldNativeAccess_1_15_2.java b/worldedit-bukkit/src/main/java/com/boydti/fawe/bukkit/adapter/mc1_15_2/FAWEWorldNativeAccess_1_15_2.java
index a61dd262d..4e6f03370 100644
--- a/worldedit-bukkit/src/main/java/com/boydti/fawe/bukkit/adapter/mc1_15_2/FAWEWorldNativeAccess_1_15_2.java
+++ b/worldedit-bukkit/src/main/java/com/boydti/fawe/bukkit/adapter/mc1_15_2/FAWEWorldNativeAccess_1_15_2.java
@@ -196,11 +196,11 @@ public class FAWEWorldNativeAccess_1_15_2 implements WorldNativeAccess<Chunk, IB
     }
 
     private synchronized void flushAsync(final boolean sendChunks) {
-        final Set<CachedChange> changes = Collections.unmodifiableSet(cachedChanges);
+        final Set<CachedChange> changes = Collections.unmodifiableSet(new HashSet<>(cachedChanges));
         cachedChanges.clear();
         final Set<IntPair> toSend;
         if (sendChunks) {
-            toSend = Collections.unmodifiableSet(cachedChunksToSend);
+            toSend = Collections.unmodifiableSet(new HashSet<>(cachedChunksToSend));
             cachedChunksToSend.clear();
         } else {
             toSend = Collections.emptySet();
diff --git a/worldedit-bukkit/src/main/java/com/boydti/fawe/bukkit/adapter/mc1_16_1/FAWEWorldNativeAccess_1_16_R1.java b/worldedit-bukkit/src/main/java/com/boydti/fawe/bukkit/adapter/mc1_16_1/FAWEWorldNativeAccess_1_16_R1.java
index 3be1c112b..5032c15eb 100644
--- a/worldedit-bukkit/src/main/java/com/boydti/fawe/bukkit/adapter/mc1_16_1/FAWEWorldNativeAccess_1_16_R1.java
+++ b/worldedit-bukkit/src/main/java/com/boydti/fawe/bukkit/adapter/mc1_16_1/FAWEWorldNativeAccess_1_16_R1.java
@@ -197,11 +197,11 @@ public class FAWEWorldNativeAccess_1_16_R1 implements WorldNativeAccess<Chunk, I
     }
 
     private synchronized void flushAsync(final boolean sendChunks) {
-        final Set<CachedChange> changes = Collections.unmodifiableSet(cachedChanges);
+        final Set<CachedChange> changes = Collections.unmodifiableSet(new HashSet<>(cachedChanges));
         cachedChanges.clear();
         final Set<IntPair> toSend;
         if (sendChunks) {
-            toSend = Collections.unmodifiableSet(cachedChunksToSend);
+            toSend = Collections.unmodifiableSet(new HashSet<>(cachedChunksToSend));
             cachedChunksToSend.clear();
         } else {
             toSend = Collections.emptySet();
diff --git a/worldedit-bukkit/src/main/java/com/boydti/fawe/bukkit/adapter/mc1_16_2/FAWEWorldNativeAccess_1_16_R2.java b/worldedit-bukkit/src/main/java/com/boydti/fawe/bukkit/adapter/mc1_16_2/FAWEWorldNativeAccess_1_16_R2.java
index 7317a7c76..e02b833d8 100644
--- a/worldedit-bukkit/src/main/java/com/boydti/fawe/bukkit/adapter/mc1_16_2/FAWEWorldNativeAccess_1_16_R2.java
+++ b/worldedit-bukkit/src/main/java/com/boydti/fawe/bukkit/adapter/mc1_16_2/FAWEWorldNativeAccess_1_16_R2.java
@@ -197,11 +197,11 @@ public class FAWEWorldNativeAccess_1_16_R2 implements WorldNativeAccess<Chunk, I
     }
 
     private synchronized void flushAsync(final boolean sendChunks) {
-        final Set<CachedChange> changes = Collections.unmodifiableSet(cachedChanges);
+        final Set<CachedChange> changes = Collections.unmodifiableSet(new HashSet<>(cachedChanges));
         cachedChanges.clear();
         final Set<IntPair> toSend;
         if (sendChunks) {
-            toSend = Collections.unmodifiableSet(cachedChunksToSend);
+            toSend = Collections.unmodifiableSet(new HashSet<>(cachedChunksToSend));
             cachedChunksToSend.clear();
         } else {
             toSend = Collections.emptySet();
diff --git a/worldedit-bukkit/src/main/java/com/boydti/fawe/bukkit/adapter/mc1_16_5/FAWEWorldNativeAccess_1_16_R3.java b/worldedit-bukkit/src/main/java/com/boydti/fawe/bukkit/adapter/mc1_16_5/FAWEWorldNativeAccess_1_16_R3.java
index 2795bb0a2..c5e2c3dd9 100644
--- a/worldedit-bukkit/src/main/java/com/boydti/fawe/bukkit/adapter/mc1_16_5/FAWEWorldNativeAccess_1_16_R3.java
+++ b/worldedit-bukkit/src/main/java/com/boydti/fawe/bukkit/adapter/mc1_16_5/FAWEWorldNativeAccess_1_16_R3.java
@@ -196,11 +196,11 @@ public class FAWEWorldNativeAccess_1_16_R3 implements WorldNativeAccess<Chunk, I
     }
 
     private synchronized void flushAsync(final boolean sendChunks) {
-        final Set<CachedChange> changes = Collections.unmodifiableSet(cachedChanges);
+        final Set<CachedChange> changes = Collections.unmodifiableSet(new HashSet<>(cachedChanges));
         cachedChanges.clear();
         final Set<IntPair> toSend;
         if (sendChunks) {
-            toSend = Collections.unmodifiableSet(cachedChunksToSend);
+            toSend = Collections.unmodifiableSet(new HashSet<>(cachedChunksToSend));
             cachedChunksToSend.clear();
         } else {
             toSend = Collections.emptySet();