diff --git a/classlib/src/main/java/org/teavm/classlib/java/lang/TObject.java b/classlib/src/main/java/org/teavm/classlib/java/lang/TObject.java
index 7e1051975..27bcabd0c 100644
--- a/classlib/src/main/java/org/teavm/classlib/java/lang/TObject.java
+++ b/classlib/src/main/java/org/teavm/classlib/java/lang/TObject.java
@@ -186,6 +186,10 @@ public class TObject {
         if (monitor == null) {
             return true;
         }
+        if (PlatformDetector.isWebAssemblyGC()) {
+            // TODO: fix Monitor implementation and remove this block
+            return monitor.owner == null;
+        }
         if (monitor.owner == null
                 && (monitor.enteringThreads == null || monitor.enteringThreads.isEmpty())
                 && (monitor.notifyListeners == null || monitor.notifyListeners.isEmpty())) {
diff --git a/jso/impl/src/main/java/org/teavm/jso/impl/JSOPlugin.java b/jso/impl/src/main/java/org/teavm/jso/impl/JSOPlugin.java
index 5ef5e7784..2d62ed117 100644
--- a/jso/impl/src/main/java/org/teavm/jso/impl/JSOPlugin.java
+++ b/jso/impl/src/main/java/org/teavm/jso/impl/JSOPlugin.java
@@ -31,6 +31,12 @@ import org.teavm.vm.spi.TeaVMPlugin;
 public class JSOPlugin implements TeaVMPlugin {
     @Override
     public void install(TeaVMHost host) {
+        var jsHost = host.getExtension(TeaVMJavaScriptHost.class);
+        var wasmGCHost = host.getExtension(TeaVMWasmGCHost.class);
+        if (jsHost == null && wasmGCHost == null) {
+            return;
+        }
+
         JSBodyRepository repository = new JSBodyRepository();
         host.registerService(JSBodyRepository.class, repository);
         host.add(new JSObjectClassTransformer(repository));
@@ -48,12 +54,10 @@ public class JSOPlugin implements TeaVMPlugin {
 
         TeaVMPluginUtil.handleNatives(host, JS.class);
 
-        var jsHost = host.getExtension(TeaVMJavaScriptHost.class);
         if (jsHost != null) {
             installForJS(jsHost);
         }
 
-        var wasmGCHost = host.getExtension(TeaVMWasmGCHost.class);
         if (wasmGCHost != null) {
             WasmGCJso.install(host, wasmGCHost, repository);
         }