diff --git a/src/main/java/org/embeddedt/modernfix/common/mixin/bugfix/concurrency/ReloadableResourceManagerMixin.java b/src/main/java/org/embeddedt/modernfix/common/mixin/bugfix/concurrency/ReloadableResourceManagerMixin.java
new file mode 100644
index 00000000..e056c64f
--- /dev/null
+++ b/src/main/java/org/embeddedt/modernfix/common/mixin/bugfix/concurrency/ReloadableResourceManagerMixin.java
@@ -0,0 +1,49 @@
+package org.embeddedt.modernfix.common.mixin.bugfix.concurrency;
+
+import com.llamalad7.mixinextras.injector.wrapmethod.WrapMethod;
+import com.llamalad7.mixinextras.injector.wrapoperation.Operation;
+import net.minecraft.client.Minecraft;
+import net.minecraft.server.packs.PackType;
+import net.minecraft.server.packs.resources.PreparableReloadListener;
+import net.minecraft.server.packs.resources.ReloadableResourceManager;
+import net.minecraftforge.fml.ModContainer;
+import net.minecraftforge.fml.ModList;
+import net.minecraftforge.fml.ModLoadingStage;
+import net.minecraftforge.registries.ForgeRegistries;
+import org.embeddedt.modernfix.ModernFix;
+import org.embeddedt.modernfix.annotation.ClientOnlyMixin;
+import org.embeddedt.modernfix.forge.init.ModernFixForge;
+import org.spongepowered.asm.mixin.Final;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+
+@Mixin(ReloadableResourceManager.class)
+@ClientOnlyMixin
+public abstract class ReloadableResourceManagerMixin {
+    @Shadow
+    @Final
+    private PackType type;
+
+    @Shadow
+    public abstract void registerReloadListener(PreparableReloadListener listener);
+
+    /**
+     * @author embeddedt
+     * @reason complain loudly when reload listeners are being registered too late in a way that would cause
+     * concurrency issues, and prevent them from crashing the game
+     */
+    @WrapMethod(method = "registerReloadListener")
+    private void checkCallingThread(PreparableReloadListener listener, Operation<Void> original) {
+        if (ModernFixForge.registryEventsFired && this.type == PackType.CLIENT_RESOURCES
+                && (Object)this == Minecraft.getInstance().getResourceManager()
+                && !Minecraft.getInstance().isSameThread()) {
+            ModernFix.LOGGER.error("A mod is calling registerReloadListener at the wrong time. This will cause random concurrency crashes when ModernFix is not installed. Please report this to them. If you are a modder, refer to https://github.com/embeddedt/ModernFix/wiki/registerReloadListener-called-on-wrong-thread for more information.", new Exception("registerReloadListener called on wrong thread"));
+            // Defer the call onto the main client thread. There is a decent chance the mod's listener will be
+            // ignored in this case, but it is more predictable than allowing them to randomly crash the game.
+            Minecraft.getInstance().tell(() -> this.registerReloadListener(listener));
+            return;
+        }
+
+        original.call(listener);
+    }
+}
diff --git a/src/main/java/org/embeddedt/modernfix/common/mixin/core/GameDataMixin.java b/src/main/java/org/embeddedt/modernfix/common/mixin/core/GameDataMixin.java
new file mode 100644
index 00000000..3756e72b
--- /dev/null
+++ b/src/main/java/org/embeddedt/modernfix/common/mixin/core/GameDataMixin.java
@@ -0,0 +1,16 @@
+package org.embeddedt.modernfix.common.mixin.core;
+
+import net.minecraftforge.registries.GameData;
+import org.embeddedt.modernfix.forge.init.ModernFixForge;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+@Mixin(value = GameData.class, remap = false)
+public class GameDataMixin {
+    @Inject(method = "postRegisterEvents", at = @At("RETURN"))
+    private static void markPosted(CallbackInfo ci) {
+        ModernFixForge.registryEventsFired = true;
+    }
+}
diff --git a/src/main/java/org/embeddedt/modernfix/forge/init/ModernFixForge.java b/src/main/java/org/embeddedt/modernfix/forge/init/ModernFixForge.java
index dd2cd228..a95cbdd2 100644
--- a/src/main/java/org/embeddedt/modernfix/forge/init/ModernFixForge.java
+++ b/src/main/java/org/embeddedt/modernfix/forge/init/ModernFixForge.java
@@ -38,6 +38,7 @@ import java.util.List;
 public class ModernFixForge {
     private static ModernFix commonMod;
     public static boolean launchDone = false;
+    public static boolean registryEventsFired = false;
 
     public ModernFixForge() {
         commonMod = new ModernFix();