diff --git a/src/main/java/com/gtnewhorizons/postea/api/BlockReplacementManager.java b/src/main/java/com/gtnewhorizons/postea/api/BlockReplacementManager.java
index 027008a..168362d 100644
--- a/src/main/java/com/gtnewhorizons/postea/api/BlockReplacementManager.java
+++ b/src/main/java/com/gtnewhorizons/postea/api/BlockReplacementManager.java
@@ -1,14 +1,12 @@
 package com.gtnewhorizons.postea.api;
 
 import java.util.function.Consumer;
-import java.util.function.Function;
 
 import javax.annotation.Nonnull;
 
 import net.minecraft.block.Block;
 import net.minecraftforge.oredict.OreDictionary;
 
-import com.gtnewhorizons.postea.utility.BlockConversionInfo;
 import com.gtnewhorizons.postea.utility.IDRegistry;
 import com.gtnewhorizons.postea.utility.MissingMappingHandler;
 import com.gtnewhorizons.postea.utility.SimpleTransformationRegistry;
@@ -48,7 +46,7 @@ public abstract class BlockReplacementManager {
      * @param transformer The transformer to apply.
      */
     @SuppressWarnings("unused")
-    public static void addTransformationHandler(String originalId, Function<BlockConversionInfo, Boolean> transformer) {
+    public static void addTransformationHandler(String originalId, IBlockTransformationHandler transformer) {
         if (originalId == null) throw new IllegalArgumentException("original id is null");
         if (transformer == null) throw new IllegalArgumentException("transformer is null");
         TransformerRegistry.addBlockTransformer(originalId, transformer);
diff --git a/src/main/java/com/gtnewhorizons/postea/api/IBlockTransformationHandler.java b/src/main/java/com/gtnewhorizons/postea/api/IBlockTransformationHandler.java
new file mode 100644
index 0000000..e183082
--- /dev/null
+++ b/src/main/java/com/gtnewhorizons/postea/api/IBlockTransformationHandler.java
@@ -0,0 +1,9 @@
+package com.gtnewhorizons.postea.api;
+
+import com.gtnewhorizons.postea.utility.BlockConversionInfo;
+
+@FunctionalInterface
+public interface IBlockTransformationHandler {
+
+    boolean apply(BlockConversionInfo info);
+}
diff --git a/src/main/java/com/gtnewhorizons/postea/api/IItemStackTransformationHandler.java b/src/main/java/com/gtnewhorizons/postea/api/IItemStackTransformationHandler.java
new file mode 100644
index 0000000..d4be2dd
--- /dev/null
+++ b/src/main/java/com/gtnewhorizons/postea/api/IItemStackTransformationHandler.java
@@ -0,0 +1,9 @@
+package com.gtnewhorizons.postea.api;
+
+import net.minecraft.nbt.NBTTagCompound;
+
+@FunctionalInterface
+public interface IItemStackTransformationHandler {
+
+    boolean apply(String originalId, NBTTagCompound stack);
+}
diff --git a/src/main/java/com/gtnewhorizons/postea/api/ItemStackReplacementManager.java b/src/main/java/com/gtnewhorizons/postea/api/ItemStackReplacementManager.java
index 51a0063..949e126 100644
--- a/src/main/java/com/gtnewhorizons/postea/api/ItemStackReplacementManager.java
+++ b/src/main/java/com/gtnewhorizons/postea/api/ItemStackReplacementManager.java
@@ -1,6 +1,5 @@
 package com.gtnewhorizons.postea.api;
 
-import java.util.function.BiFunction;
 import java.util.function.Consumer;
 
 import javax.annotation.Nonnull;
@@ -8,7 +7,6 @@
 import net.minecraft.init.Items;
 import net.minecraft.item.Item;
 import net.minecraft.item.ItemStack;
-import net.minecraft.nbt.NBTTagCompound;
 import net.minecraftforge.oredict.OreDictionary;
 
 import com.gtnewhorizons.postea.utility.IDRegistry;
@@ -52,8 +50,7 @@ public abstract class ItemStackReplacementManager {
      * @param transformer The transformer to apply.
      */
     @SuppressWarnings("unused")
-    public static void addTransformationHandler(String originalId,
-        BiFunction<String, NBTTagCompound, Boolean> transformer) {
+    public static void addTransformationHandler(String originalId, IItemStackTransformationHandler transformer) {
         if (originalId == null) throw new IllegalArgumentException("original id is null");
         if (transformer == null) throw new IllegalArgumentException("transformer is null");
         TransformerRegistry.addStackTransformer(originalId, transformer);
diff --git a/src/main/java/com/gtnewhorizons/postea/utility/SimpleTransformationRegistry.java b/src/main/java/com/gtnewhorizons/postea/utility/SimpleTransformationRegistry.java
index 815546c..38a2586 100644
--- a/src/main/java/com/gtnewhorizons/postea/utility/SimpleTransformationRegistry.java
+++ b/src/main/java/com/gtnewhorizons/postea/utility/SimpleTransformationRegistry.java
@@ -1,8 +1,6 @@
 package com.gtnewhorizons.postea.utility;
 
 import java.util.Map;
-import java.util.function.BiFunction;
-import java.util.function.Function;
 
 import net.minecraft.block.Block;
 import net.minecraft.item.Item;
@@ -10,7 +8,9 @@
 import net.minecraft.nbt.NBTTagCompound;
 import net.minecraftforge.oredict.OreDictionary;
 
+import com.gtnewhorizons.postea.api.IBlockTransformationHandler;
 import com.gtnewhorizons.postea.api.IDExtenderCompat;
+import com.gtnewhorizons.postea.api.IItemStackTransformationHandler;
 
 /**
  * A registry for simple item and block transformations. A common use case is mod removal, replacements or deprecations.
@@ -114,7 +114,7 @@ public static void addSimpleTransformer(String originalId, int originalMeta, Blo
      *
      * @implNote This implementation has constant-time runtime.
      */
-    private static class SimpleBlockTransformationHandler implements Function<BlockConversionInfo, Boolean> {
+    private static class SimpleBlockTransformationHandler implements IBlockTransformationHandler {
 
         private final Map<Integer, SimpleTransformationMap.Value<Block>> metaMap;
 
@@ -123,7 +123,7 @@ private static class SimpleBlockTransformationHandler implements Function<BlockC
         }
 
         @Override
-        public Boolean apply(BlockConversionInfo info) {
+        public boolean apply(BlockConversionInfo info) {
             SimpleTransformationMap.Value<Block> mapping = SimpleTransformationMap
                 .getFromSubMap(metaMap, info.metadata);
             if (mapping == null || mapping.targetRuntimeId <= -1) return false;
@@ -176,7 +176,7 @@ public static void addSimpleTransformer(String originalId, int originalMeta, Ite
      *
      * @implNote This implementation has constant-time runtime.
      */
-    private static class SimpleItemTransformationHandler implements BiFunction<String, NBTTagCompound, Boolean> {
+    private static class SimpleItemTransformationHandler implements IItemStackTransformationHandler {
 
         private final Map<Integer, SimpleTransformationMap.Value<Item>> metaMap;
 
@@ -185,7 +185,7 @@ private static class SimpleItemTransformationHandler implements BiFunction<Strin
         }
 
         @Override
-        public Boolean apply(String originalId, NBTTagCompound tag) {
+        public boolean apply(String originalId, NBTTagCompound tag) {
             short meta = tag.getShort("Damage");
             SimpleTransformationMap.Value<Item> mapping = SimpleTransformationMap.getFromSubMap(metaMap, meta);
             if (mapping == null || mapping.targetRuntimeId <= -1) return false;
diff --git a/src/main/java/com/gtnewhorizons/postea/utility/TransformerRegistry.java b/src/main/java/com/gtnewhorizons/postea/utility/TransformerRegistry.java
index 7b8c4be..aec6bc1 100644
--- a/src/main/java/com/gtnewhorizons/postea/utility/TransformerRegistry.java
+++ b/src/main/java/com/gtnewhorizons/postea/utility/TransformerRegistry.java
@@ -2,8 +2,6 @@
 
 import java.util.Collection;
 import java.util.List;
-import java.util.function.BiFunction;
-import java.util.function.Function;
 
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
@@ -15,7 +13,9 @@
 import org.apache.commons.lang3.tuple.Pair;
 
 import com.google.common.collect.LinkedListMultimap;
+import com.gtnewhorizons.postea.api.IBlockTransformationHandler;
 import com.gtnewhorizons.postea.api.IDExtenderCompat;
+import com.gtnewhorizons.postea.api.IItemStackTransformationHandler;
 import com.gtnewhorizons.postea.api.TriFunction;
 
 import cpw.mods.fml.common.Loader;
@@ -27,9 +27,9 @@
  */
 public class TransformerRegistry {
 
-    private static final LinkedListMultimap<String, BiFunction<String, NBTTagCompound, Boolean>> ITEM_REPLACEMENT_MAP = LinkedListMultimap
+    private static final LinkedListMultimap<String, IItemStackTransformationHandler> ITEM_REPLACEMENT_MAP = LinkedListMultimap
         .create();
-    public static final LinkedListMultimap<String, Function<BlockConversionInfo, Boolean>> BLOCK_REPLACEMENT_MAP = LinkedListMultimap
+    public static final LinkedListMultimap<String, IBlockTransformationHandler> BLOCK_REPLACEMENT_MAP = LinkedListMultimap
         .create();
     private static final LinkedListMultimap<String, TriFunction<NBTTagCompound, World, Chunk, BlockInfo>> TILE_ENTITY_REPLACEMENT_MAP = LinkedListMultimap
         .create();
@@ -38,13 +38,13 @@ public class TransformerRegistry {
      * Pivoting on the id is faster than pivoting on the strings so this should help with perf a bit.
      * Generated during the mapping update event whilst entering/loading a world.
      */
-    private static final Int2ObjectOpenHashMap<Pair<String, List<BiFunction<String, NBTTagCompound, Boolean>>>> RUNTIME_ITEM_REPLACEMENT_MAP = new Int2ObjectOpenHashMap<>();
+    private static final Int2ObjectOpenHashMap<Pair<String, List<IItemStackTransformationHandler>>> RUNTIME_ITEM_REPLACEMENT_MAP = new Int2ObjectOpenHashMap<>();
     /**
      * Map of blockIO -> originalName+transformationHandler.
      * Pivoting on the id is faster than pivoting on the strings so this should help with perf a bit.
      * Generated during the mapping update event whilst entering/loading a world.
      */
-    private static final Int2ObjectOpenHashMap<Pair<String, List<Function<BlockConversionInfo, Boolean>>>> RUNTIME_BLOCK_REPLACEMENT_MAP = new Int2ObjectOpenHashMap<>();
+    private static final Int2ObjectOpenHashMap<Pair<String, List<IBlockTransformationHandler>>> RUNTIME_BLOCK_REPLACEMENT_MAP = new Int2ObjectOpenHashMap<>();
 
     // region FML Life Cycle handlers
     /**
@@ -94,7 +94,7 @@ public static void onIdMappingsChanged() {
      * @param transformer The transformation handler that will execute a transformation on the block.
      */
     public static void addBlockTransformer(@Nonnull String originalId,
-        @Nonnull Function<BlockConversionInfo, Boolean> transformer) {
+        @Nonnull IBlockTransformationHandler transformer) {
         BLOCK_REPLACEMENT_MAP.put(originalId, transformer);
     }
 
@@ -112,7 +112,7 @@ public static void addBlockTransformer(@Nonnull String originalId,
      * @param transformer The transformation handler that will execute a transformation on the block.
      */
     public static void addStackTransformer(@Nonnull String originalId,
-        @Nonnull BiFunction<String, NBTTagCompound, Boolean> transformer) {
+        @Nonnull IItemStackTransformationHandler transformer) {
         ITEM_REPLACEMENT_MAP.put(originalId, transformer);
     }
 
@@ -137,7 +137,7 @@ public static void addTileEntityTransformer(@Nonnull String originalId,
     // region transformation handlers
     public static @Nullable BlockConversionInfo getBlockReplacement(int blockId, byte metadata, World world, int x,
         int y, int z) {
-        Pair<String, List<Function<BlockConversionInfo, Boolean>>> data = RUNTIME_BLOCK_REPLACEMENT_MAP.get(blockId);
+        Pair<String, List<IBlockTransformationHandler>> data = RUNTIME_BLOCK_REPLACEMENT_MAP.get(blockId);
         if (data == null) return null;
         BlockConversionInfo blockConversionInfo = new BlockConversionInfo(
             // transparently maps the id to the original id if it's a dummy id
@@ -148,7 +148,7 @@ public static void addTileEntityTransformer(@Nonnull String originalId,
             y,
             z,
             world);
-        for (Function<BlockConversionInfo, Boolean> transformer : data.getValue()) {
+        for (IBlockTransformationHandler transformer : data.getValue()) {
             if (transformer.apply(blockConversionInfo)) {
                 return blockConversionInfo;
             }
@@ -161,12 +161,12 @@ public static void transformItem(NBTTagCompound tag) {
         if (tag.hasNoTags() || !tag.hasKey("id")) return;
         // get handler
         int id = IDExtenderCompat.getItemStackID(tag);
-        Pair<String, List<BiFunction<String, NBTTagCompound, Boolean>>> data = RUNTIME_ITEM_REPLACEMENT_MAP.get(id);
+        Pair<String, List<IItemStackTransformationHandler>> data = RUNTIME_ITEM_REPLACEMENT_MAP.get(id);
         // abort early if handler not found
         if (data != null && !data.getValue()
             .isEmpty()) {
             // apply handlers
-            for (BiFunction<String, NBTTagCompound, Boolean> transformer : data.getValue()) {
+            for (IItemStackTransformationHandler transformer : data.getValue()) {
                 if (transformer.apply(data.getKey(), tag)) {
                     return;
                 }