diff --git a/engine/runtime/src/main/java/org/enso/interpreter/runtime/EnsoContext.java b/engine/runtime/src/main/java/org/enso/interpreter/runtime/EnsoContext.java
index 5abee4234697..c72db6dcb655 100644
--- a/engine/runtime/src/main/java/org/enso/interpreter/runtime/EnsoContext.java
+++ b/engine/runtime/src/main/java/org/enso/interpreter/runtime/EnsoContext.java
@@ -164,6 +164,9 @@ public EnsoContext(
             scala.Option.empty());
     this.home = home;
     this.builtins = new Builtins(this);
+    // Insert default host class loader.
+    var builtinsLibName = new LibraryName(Builtins.NAMESPACE, Builtins.PACKAGE_NAME);
+    this.hostClassLoaders.put(builtinsLibName, new HostClassLoader(null));
     this.notificationHandler = notificationHandler;
     this.lockManager = lockManager;
     this.distributionManager = distributionManager;
diff --git a/engine/runtime/src/main/java/org/enso/interpreter/runtime/HostClassLoader.java b/engine/runtime/src/main/java/org/enso/interpreter/runtime/HostClassLoader.java
index 69c61274454d..0ac2923b8e1e 100644
--- a/engine/runtime/src/main/java/org/enso/interpreter/runtime/HostClassLoader.java
+++ b/engine/runtime/src/main/java/org/enso/interpreter/runtime/HostClassLoader.java
@@ -3,7 +3,6 @@
 import com.oracle.truffle.api.TruffleFile;
 import java.net.URL;
 import java.net.URLClassLoader;
-import java.util.Locale;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 import org.enso.pkg.Package;
@@ -37,7 +36,7 @@ final class HostClassLoader extends URLClassLoader implements AutoCloseable {
   public HostClassLoader(Package<TruffleFile> pkg) {
     super(new URL[0]);
     this.pkg = pkg;
-    assert pkg.polyglotDir().exists();
+    assert pkg == null || pkg.polyglotDir().exists();
   }
 
   static {
@@ -95,6 +94,10 @@ public void close() {
 
   @Override
   public String toString() {
-    return "HostClassLoader(" + pkg.libraryName() + ")";
+    if (pkg != null) {
+      return "HostClassLoader(" + pkg.libraryName() + ")";
+    } else {
+      return "HostClassLoader";
+    }
   }
 }