diff --git a/CHANGELOG.md b/CHANGELOG.md
index a7a7981faf..fc1a6126a6 100755
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ### 1.6.5
 - Fixed Refined Storage silicon's oredict entry being registered too late (raoulvdberge)
+- Fixed duplication bug with filter slots (raoulvdberge)
 - The Pattern Grid in fluid mode now supports up to 64 buckets in the input and output processing slots (raoulvdberge)
 
 ### 1.6.4
diff --git a/src/main/java/com/raoulvdberge/refinedstorage/container/ContainerBase.java b/src/main/java/com/raoulvdberge/refinedstorage/container/ContainerBase.java
index bbb902fe37..35e3403eca 100755
--- a/src/main/java/com/raoulvdberge/refinedstorage/container/ContainerBase.java
+++ b/src/main/java/com/raoulvdberge/refinedstorage/container/ContainerBase.java
@@ -143,6 +143,15 @@ public boolean canInteractWith(EntityPlayer player) {
         return true;
     }
 
+    @Override
+    public boolean canMergeSlot(ItemStack stack, Slot slot) {
+        if (slot instanceof SlotFilter || slot instanceof SlotFilterFluid || slot instanceof SlotLegacyFilter) {
+            return false;
+        }
+
+        return super.canMergeSlot(stack, slot);
+    }
+
     protected boolean isHeldItemDisabled() {
         return false;
     }
diff --git a/src/main/java/com/raoulvdberge/refinedstorage/container/ContainerGrid.java b/src/main/java/com/raoulvdberge/refinedstorage/container/ContainerGrid.java
index 1f45cfe24c..3b3b79358e 100755
--- a/src/main/java/com/raoulvdberge/refinedstorage/container/ContainerGrid.java
+++ b/src/main/java/com/raoulvdberge/refinedstorage/container/ContainerGrid.java
@@ -250,7 +250,11 @@ public void onContainerClosed(EntityPlayer player) {
 
     @Override
     public boolean canMergeSlot(ItemStack stack, Slot slot) {
-        return (slot == craftingResultSlot || slot == patternResultSlot) ? false : super.canMergeSlot(stack, slot);
+        if (slot == craftingResultSlot || slot == patternResultSlot) {
+            return false;
+        }
+
+        return super.canMergeSlot(stack, slot);
     }
 
     @Override