diff --git a/conf/build.gradle.forge b/conf/build.gradle.forge
index 46df073..940c0d9 100644
--- a/conf/build.gradle.forge
+++ b/conf/build.gradle.forge
@@ -26,7 +26,7 @@
 
 dependencies
 {
-    compile 'net.minecraft:launchwrapper:1.11'
+    compile 'net.minecraft:launchwrapper:1.12'
     compile 'com.google.code.findbugs:jsr305:1.3.9'
     compile 'org.ow2.asm:asm-debug-all:5.0.3'
     compile 'com.typesafe.akka:akka-actor_2.11:2.3.3'
diff --git a/src/main/java/cpw/mods/fml/relauncher/CoreModManager.java b/src/main/java/cpw/mods/fml/relauncher/CoreModManager.java
index 7c76d59..24742c7 100644
--- a/src/main/java/cpw/mods/fml/relauncher/CoreModManager.java
+++ b/src/main/java/cpw/mods/fml/relauncher/CoreModManager.java
@@ -13,24 +13,30 @@
 package cpw.mods.fml.relauncher;
 
 import java.io.File;
+import java.io.FileFilter;
 import java.io.FilenameFilter;
 import java.io.IOException;
+import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.net.MalformedURLException;
 import java.net.URL;
 import java.net.URLClassLoader;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Calendar;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.jar.Attributes;
 import java.util.jar.JarFile;
+
 import net.minecraft.launchwrapper.ITweaker;
 import net.minecraft.launchwrapper.Launch;
 import net.minecraft.launchwrapper.LaunchClassLoader;
+
 import org.apache.logging.log4j.Level;
+
 import com.google.common.base.Strings;
 import com.google.common.base.Throwables;
 import com.google.common.collect.ImmutableList;
@@ -38,6 +44,7 @@
 import com.google.common.collect.Maps;
 import com.google.common.collect.ObjectArrays;
 import com.google.common.primitives.Ints;
+
 import cpw.mods.fml.common.FMLLog;
 import cpw.mods.fml.common.asm.transformers.ModAccessTransformer;
 import cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker;
@@ -243,6 +250,42 @@
 				FMLRelaunchLog.severe("Problem file : %s", f.getName());
 			}
 		}
+		FileFilter derpdirfilter = new FileFilter() {
+			@Override
+			public boolean accept(File pathname)
+			{
+				return pathname.isDirectory() && new File(pathname,"META-INF").isDirectory();
+			}
+
+		};
+		File[] derpdirlist = coreMods.listFiles(derpdirfilter);
+		if (derpdirlist != null && derpdirlist.length > 0)
+		{
+			FMLRelaunchLog.log.getLogger().log(Level.FATAL, "There appear to be jars extracted into the mods directory. This is VERY BAD and will almost NEVER WORK WELL");
+			FMLRelaunchLog.log.getLogger().log(Level.FATAL, "You should place original jars only in the mods directory. NEVER extract them to the mods directory.");
+			FMLRelaunchLog.log.getLogger().log(Level.FATAL, "The directories below appear to be extracted jar files. Fix this before you continue.");
+
+			for (File f : derpdirlist)
+			{
+				FMLRelaunchLog.log.getLogger().log(Level.FATAL, "Directory {} contains {}", f.getName(), Arrays.asList(new File(f,"META-INF").list()));
+			}
+
+			RuntimeException re = new RuntimeException("Extracted mod jars found, loading will NOT continue");
+			// We're generating a crash report for the launcher to show to the user here
+			try
+			{
+				Class<?> crashreportclass = classLoader.loadClass("b");
+				Object crashreport = crashreportclass.getMethod("a", Throwable.class, String.class).invoke(null, re, "FML has discovered extracted jar files in the mods directory.\nThis breaks mod loading functionality completely.\nRemove the directories and replace with the jar files originally provided.");
+				File crashreportfile = new File(new File(coreMods.getParentFile(),"crash-reports"),String.format("fml-crash-%1$tY-%1$tm-%1$td_%1$tT.txt",Calendar.getInstance()));
+				crashreportclass.getMethod("a",File.class).invoke(crashreport, crashreportfile);
+				System.out.println("#@!@# FML has crashed the game deliberately. Crash report saved to: #@!@# " + crashreportfile.getAbsolutePath());
+			} catch (Exception e)
+			{
+				e.printStackTrace();
+				// NOOP - hopefully
+			}
+			throw re;
+		}
 		File[] coreModList = coreMods.listFiles(ff);
 		File versionedModDir = new File(coreMods, FMLInjectionData.mccversion);
 		if (versionedModDir.isDirectory())