diff --git a/src/main/java/org/embeddedt/modernfix/core/config/ModernFixEarlyConfig.java b/src/main/java/org/embeddedt/modernfix/core/config/ModernFixEarlyConfig.java
index 35a1b441..d4c8e106 100644
--- a/src/main/java/org/embeddedt/modernfix/core/config/ModernFixEarlyConfig.java
+++ b/src/main/java/org/embeddedt/modernfix/core/config/ModernFixEarlyConfig.java
@@ -29,6 +29,7 @@ public class ModernFixEarlyConfig {
         this.addMixinRule("bugfix.concurrency", true);
         this.addMixinRule("bugfix.edge_chunk_not_saved", true);
         this.addMixinRule("bugfix.packet_leak", false);
+        this.addMixinRule("bugfix.structure_manager_crash", true);
         this.addMixinRule("perf.async_jei", true);
         this.addMixinRule("perf.thread_priorities", true);
         this.addMixinRule("perf.preload_block_classes", false);
diff --git a/src/main/java/org/embeddedt/modernfix/mixin/bugfix/structure_manager_crash/StructureManagerMixin.java b/src/main/java/org/embeddedt/modernfix/mixin/bugfix/structure_manager_crash/StructureManagerMixin.java
new file mode 100644
index 00000000..5aacf946
--- /dev/null
+++ b/src/main/java/org/embeddedt/modernfix/mixin/bugfix/structure_manager_crash/StructureManagerMixin.java
@@ -0,0 +1,27 @@
+package org.embeddedt.modernfix.mixin.bugfix.structure_manager_crash;
+
+import com.mojang.datafixers.DataFixer;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.server.packs.resources.ResourceManager;
+import net.minecraft.world.level.levelgen.structure.templatesystem.StructureManager;
+import net.minecraft.world.level.levelgen.structure.templatesystem.StructureTemplate;
+import net.minecraft.world.level.storage.LevelStorageSource;
+import org.spongepowered.asm.mixin.Final;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+import java.util.Collections;
+import java.util.Map;
+
+@Mixin(StructureManager.class)
+public class StructureManagerMixin {
+    @Shadow @Final private Map<ResourceLocation, StructureTemplate> structureRepository;
+
+    @Inject(method = "<init>", at = @At("RETURN"))
+    private void makeStructuresSafe(ResourceManager arg, LevelStorageSource.LevelStorageAccess arg2, DataFixer dataFixer, CallbackInfo ci) {
+        this.structureRepository = Collections.synchronizedMap(this.structureRepository);
+    }
+}
diff --git a/src/main/resources/modernfix.mixins.json b/src/main/resources/modernfix.mixins.json
index 036f121a..909005af 100644
--- a/src/main/resources/modernfix.mixins.json
+++ b/src/main/resources/modernfix.mixins.json
@@ -7,6 +7,7 @@
   "refmap": "modernfix.refmap.json",
   "mixins": [
     "bugfix.edge_chunk_not_saved.ChunkManagerMixin",
+    "bugfix.structure_manager_crash.StructureManagerMixin",
     "perf.remove_biome_temperature_cache.BiomeMixin",
     "perf.resourcepacks.ModFileResourcePackMixin",
     "perf.resourcepacks.VanillaPackMixin",