diff --git a/common/src/main/java/org/embeddedt/modernfix/command/ModernFixCommands.java b/common/src/main/java/org/embeddedt/modernfix/command/ModernFixCommands.java
index a4431a35..97fcda8c 100644
--- a/common/src/main/java/org/embeddedt/modernfix/command/ModernFixCommands.java
+++ b/common/src/main/java/org/embeddedt/modernfix/command/ModernFixCommands.java
@@ -7,15 +7,15 @@ import net.minecraft.resources.ResourceLocation;
 import net.minecraft.server.level.ServerLevel;
 import net.minecraft.server.packs.resources.Resource;
 import net.minecraft.server.packs.resources.ResourceManager;
+import org.embeddedt.modernfix.ModernFix;
 import org.embeddedt.modernfix.structure.CachingStructureManager;
 
-import java.io.IOException;
 import java.io.InputStream;
 import java.util.Map;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
-import static net.minecraft.commands.Commands.*;
+import static net.minecraft.commands.Commands.literal;
 
 public class ModernFixCommands {
     public static void register(CommandDispatcher<CommandSourceStack> dispatcher) {
@@ -43,7 +43,8 @@ public class ModernFixCommands {
                                 try(InputStream resource = entry.getValue().open()) {
                                     CachingStructureManager.readStructureTag(structureLocation, level.getServer().getFixerUpper(), resource);
                                     context.getSource().sendSuccess(Component.literal("checked " + structureLocation + " (" + upgradedNum + "/" + structures.size() + ")"), false);
-                                } catch(IOException e) {
+                                } catch(Throwable e) {
+                                    ModernFix.LOGGER.error("Couldn't upgrade structure " + found, e);
                                     context.getSource().sendFailure(Component.literal("error reading " + structureLocation + " (" + upgradedNum + "/" + structures.size() + ")"));
                                 }
                             }
diff --git a/common/src/main/java/org/embeddedt/modernfix/dfu/DFUBlaster.java b/common/src/main/java/org/embeddedt/modernfix/dfu/DFUBlaster.java
index b1d78509..bd1b0c5f 100644
--- a/common/src/main/java/org/embeddedt/modernfix/dfu/DFUBlaster.java
+++ b/common/src/main/java/org/embeddedt/modernfix/dfu/DFUBlaster.java
@@ -17,15 +17,13 @@ import java.util.concurrent.TimeUnit;
 import java.util.function.IntFunction;
 
 public class DFUBlaster {
+    private static final Cache<Pair<IntFunction<RewriteResult<?, ?>>, Integer>, RewriteResult<?, ?>> hmapApplyCache = CacheBuilder.newBuilder()
+            .expireAfterAccess(3, TimeUnit.MINUTES)
+            .build();
+    private static final Cache<Triple<Type<?>, TypeRewriteRule, PointFreeRule>, Optional<? extends RewriteResult<?, ?>>> rewriteCache = CacheBuilder.newBuilder()
+            .expireAfterAccess(3, TimeUnit.MINUTES)
+            .build();
     public static void blastMaps() {
-        Cache<Pair<IntFunction<RewriteResult<?, ?>>, Integer>, RewriteResult<?, ?>> hmapApplyCache = CacheBuilder.newBuilder()
-                .maximumSize(200) /* should mean approximately 50MB used max */
-                .expireAfterAccess(3, TimeUnit.MINUTES)
-                .build();
-        Cache<Triple<Type<?>, TypeRewriteRule, PointFreeRule>, Optional<? extends RewriteResult<?, ?>>> rewriteCache = CacheBuilder.newBuilder()
-                .maximumSize(1000)
-                .expireAfterAccess(3, TimeUnit.MINUTES)
-                .build();
         try {
             Class<?> FOLD_CLASS = Class.forName("com.mojang.datafixers.functions.Fold");
             Field hmapField = FOLD_CLASS.getDeclaredField("HMAP_APPLY_CACHE");
@@ -41,8 +39,30 @@ public class DFUBlaster {
             base = unsafe.staticFieldBase(rewriteCacheField);
             offset = unsafe.staticFieldOffset(rewriteCacheField);
             unsafe.putObject(base, offset, rewriteCache.asMap());
+            new CleanerThread().start();
         } catch(Throwable e) {
             ModernFix.LOGGER.error("Could not replace DFU map", e);
         }
     }
+
+    static class CleanerThread extends Thread {
+        CleanerThread() {
+            this.setName("DFU cleaning thread");
+            this.setPriority(1);
+            this.setDaemon(true);
+        }
+
+        @Override
+        public void run() {
+            while(true) {
+                try {
+                    Thread.sleep(15000);
+                } catch(InterruptedException e){
+                    return;
+                }
+                rewriteCache.cleanUp();
+                hmapApplyCache.cleanUp();
+            }
+        }
+    }
 }
diff --git a/common/src/main/java/org/embeddedt/modernfix/dfu/LazyDataFixer.java b/common/src/main/java/org/embeddedt/modernfix/dfu/LazyDataFixer.java
index d8ece26c..369a5b53 100644
--- a/common/src/main/java/org/embeddedt/modernfix/dfu/LazyDataFixer.java
+++ b/common/src/main/java/org/embeddedt/modernfix/dfu/LazyDataFixer.java
@@ -35,6 +35,7 @@ public class LazyDataFixer implements DataFixer {
         synchronized (this) {
             if(backingDataFixer == null) {
                 LOGGER.info("Instantiating Mojang DFU");
+                DFUBlaster.blastMaps();
                 backingDataFixer = dfuSupplier.get();
             }
         }
diff --git a/forge/src/main/java/org/embeddedt/modernfix/platform/forge/ModernFixPlatformHooksImpl.java b/forge/src/main/java/org/embeddedt/modernfix/platform/forge/ModernFixPlatformHooksImpl.java
index 7421781e..60240a84 100644
--- a/forge/src/main/java/org/embeddedt/modernfix/platform/forge/ModernFixPlatformHooksImpl.java
+++ b/forge/src/main/java/org/embeddedt/modernfix/platform/forge/ModernFixPlatformHooksImpl.java
@@ -18,7 +18,6 @@ import net.minecraftforge.network.PacketDistributor;
 import net.minecraftforge.server.ServerLifecycleHooks;
 import org.embeddedt.modernfix.forge.classloading.FastAccessTransformerList;
 import org.embeddedt.modernfix.core.ModernFixMixinPlugin;
-import org.embeddedt.modernfix.dfu.DFUBlaster;
 import org.embeddedt.modernfix.forge.packet.PacketHandler;
 import org.embeddedt.modernfix.util.DummyList;
 import org.objectweb.asm.Opcodes;
@@ -76,7 +75,6 @@ public class ModernFixPlatformHooksImpl {
 
     public static void injectPlatformSpecificHacks() {
         FastAccessTransformerList.attemptReplace();
-        DFUBlaster.blastMaps();
 
         /* https://github.com/FabricMC/Mixin/pull/99 */
         try {