diff --git a/src/fmllauncher/java/net/minecraftforge/fml/loading/FMLCommonLaunchHandler.java b/src/fmllauncher/java/net/minecraftforge/fml/loading/FMLCommonLaunchHandler.java
index 86371eed1..4b1a85b24 100644
--- a/src/fmllauncher/java/net/minecraftforge/fml/loading/FMLCommonLaunchHandler.java
+++ b/src/fmllauncher/java/net/minecraftforge/fml/loading/FMLCommonLaunchHandler.java
@@ -23,6 +23,7 @@ import cpw.mods.modlauncher.api.IEnvironment;
 import cpw.mods.modlauncher.api.ITransformingClassLoader;
 import cpw.mods.modlauncher.api.ITransformingClassLoaderBuilder;
 import net.minecraftforge.api.distmarker.Dist;
+import net.minecraftforge.fml.loading.moddiscovery.ModFile;
 import org.apache.commons.lang3.tuple.Pair;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -41,6 +42,7 @@ import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 import static net.minecraftforge.fml.loading.LogMarkers.CORE;
+import static net.minecraftforge.fml.loading.LogMarkers.LOADING;
 
 public abstract class FMLCommonLaunchHandler
 {
@@ -54,6 +56,8 @@ public abstract class FMLCommonLaunchHandler
             "net.minecraftforge.eventbus.", "net.minecraftforge.api.", "com.mojang.util.QueueLogAppender"
     );
 
+    private final List<Path> additionalLibraries = new ArrayList<>();
+
     protected Predicate<String> getPackagePredicate() {
         return cn -> SKIPPACKAGES.stream().noneMatch(cn::startsWith);
     }
@@ -69,6 +73,7 @@ public abstract class FMLCommonLaunchHandler
     public void configureTransformationClassLoader(final ITransformingClassLoaderBuilder builder) {
         builder.addTransformationPath(FMLLoader.getForgePath());
         Arrays.stream(FMLLoader.getMCPaths()).forEach(builder::addTransformationPath);
+        additionalLibraries.forEach(builder::addTransformationPath);
         FMLLoader.getLanguageLoadingProvider().getLibraries().forEach(builder::addTransformationPath);
         builder.setClassBytesLocator(getClassLoaderLocatorFunction());
         builder.setManifestLocator(getClassLoaderManifestLocatorFunction());
@@ -137,4 +142,12 @@ public abstract class FMLCommonLaunchHandler
     }
 
     protected abstract String getNaming();
+
+    void addLibraries(final List<ModFile> libraries) {
+        libraries
+                .stream()
+                .map(ModFile::getFilePath)
+                .peek(p->LOGGER.debug(LOADING, "Adding {} as a library to the transforming classloader", p))
+                .forEach(additionalLibraries::add);
+    }
 }
diff --git a/src/fmllauncher/java/net/minecraftforge/fml/loading/FMLLoader.java b/src/fmllauncher/java/net/minecraftforge/fml/loading/FMLLoader.java
index ec8d9fa98..937e57d12 100644
--- a/src/fmllauncher/java/net/minecraftforge/fml/loading/FMLLoader.java
+++ b/src/fmllauncher/java/net/minecraftforge/fml/loading/FMLLoader.java
@@ -81,6 +81,7 @@ public class FMLLoader
     private static String forgeGroup;
     private static Predicate<String> classLoaderExclusions;
     private static String launchHandlerName;
+    private static FMLCommonLaunchHandler commonLaunchHandler;
 
     static void onInitialLoad(IEnvironment environment, Set<String> otherServices) throws IncompatibleEnvironmentException
     {
@@ -175,7 +176,7 @@ public class FMLLoader
         launchHandlerName = launchHandler.get().name();
         gamePath = environment.getProperty(IEnvironment.Keys.GAMEDIR.get()).orElse(Paths.get(".").toAbsolutePath());
 
-        FMLCommonLaunchHandler commonLaunchHandler = (FMLCommonLaunchHandler)launchHandler.get();
+        commonLaunchHandler = (FMLCommonLaunchHandler)launchHandler.get();
         naming = commonLaunchHandler.getNaming();
         dist = commonLaunchHandler.getDist();
         EarlyProgressVisualization.INSTANCE.accept(dist);
@@ -206,6 +207,7 @@ public class FMLLoader
         modDiscoverer = new ModDiscoverer(arguments);
         final BackgroundScanHandler backgroundScanHandler = modDiscoverer.discoverMods();
         loadingModList = backgroundScanHandler.getLoadingModList();
+        commonLaunchHandler.addLibraries(backgroundScanHandler.getModFiles().getOrDefault(IModFile.Type.LIBRARY, Collections.emptyList()));
         return backgroundScanHandler.getModFiles();
     }
 
diff --git a/src/fmllauncher/java/net/minecraftforge/fml/loading/moddiscovery/ModFileInfo.java b/src/fmllauncher/java/net/minecraftforge/fml/loading/moddiscovery/ModFileInfo.java
index 247cda8bf..ccf131359 100644
--- a/src/fmllauncher/java/net/minecraftforge/fml/loading/moddiscovery/ModFileInfo.java
+++ b/src/fmllauncher/java/net/minecraftforge/fml/loading/moddiscovery/ModFileInfo.java
@@ -24,6 +24,8 @@ import net.minecraftforge.forgespi.language.MavenVersionAdapter;
 import net.minecraftforge.forgespi.language.IModFileInfo;
 import net.minecraftforge.forgespi.language.IModInfo;
 import net.minecraftforge.fml.loading.StringUtils;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
 import org.apache.maven.artifact.versioning.VersionRange;
 
 import java.net.URL;
@@ -31,8 +33,11 @@ import java.util.*;
 import java.util.jar.Manifest;
 import java.util.stream.Collectors;
 
+import static net.minecraftforge.fml.loading.LogMarkers.LOADING;
+
 public class ModFileInfo implements IModFileInfo
 {
+    private static final Logger LOGGER = LogManager.getLogger();
     private final UnmodifiableConfig config;
     private final ModFile modFile;
     private final URL issueURL;
@@ -64,6 +69,10 @@ public class ModFileInfo implements IModFileInfo
         }
         this.mods = modConfigs.stream().map(mi-> new ModInfo(this, mi)).collect(Collectors.toList());
         this.issueURL = config.<String>getOptional("issueTrackerURL").map(StringUtils::toURL).orElse(null);
+        LOGGER.debug(LOADING, "Found valid mod file {} with {} mods - versions {}",
+                this.modFile::getFileName,
+                () -> mods.stream().map(IModInfo::getModId).collect(Collectors.joining(",", "{", "}")),
+                () -> mods.stream().map(IModInfo::getVersion).map(Objects::toString).collect(Collectors.joining(",", "{", "}")));
     }
 
     @Override
diff --git a/src/fmllauncher/java/net/minecraftforge/fml/loading/moddiscovery/ModFileParser.java b/src/fmllauncher/java/net/minecraftforge/fml/loading/moddiscovery/ModFileParser.java
index 018448c1c..6f59590f2 100644
--- a/src/fmllauncher/java/net/minecraftforge/fml/loading/moddiscovery/ModFileParser.java
+++ b/src/fmllauncher/java/net/minecraftforge/fml/loading/moddiscovery/ModFileParser.java
@@ -42,7 +42,7 @@ public class ModFileParser {
     private static final Logger LOGGER = LogManager.getLogger();
 
     public static IModFileInfo readModList(final ModFile modFile) {
-        LOGGER.debug(LOADING,"Parsing mod file candidate {}", modFile.getFilePath());
+        LOGGER.debug(LOADING,"Considering mod file candidate {}", modFile.getFilePath());
         final Path modsjson = modFile.getLocator().findPath(modFile, "META-INF", "mods.toml");
         if (!Files.exists(modsjson)) {
             LOGGER.warn(LOADING, "Mod file {} is missing mods.toml file", modFile);