diff --git a/core/src/main/java/org/teavm/backend/wasm/generate/gc/classes/WasmGCClassGenerator.java b/core/src/main/java/org/teavm/backend/wasm/generate/gc/classes/WasmGCClassGenerator.java
index 4fc5b5d21..280034643 100644
--- a/core/src/main/java/org/teavm/backend/wasm/generate/gc/classes/WasmGCClassGenerator.java
+++ b/core/src/main/java/org/teavm/backend/wasm/generate/gc/classes/WasmGCClassGenerator.java
@@ -157,10 +157,13 @@ public class WasmGCClassGenerator implements WasmGCClassInfoProvider, WasmGCInit
         function.getBody().addAll(initializerFunctionStatements);
         initializerFunctionStatements.clear();
         for (var classInfo : classInfoMap.values()) {
-            var supertypeFunction = supertypeGenerator.getIsSupertypeFunction(classInfo.getValueType());
-            supertypeFunction.setReferenced(true);
-            function.getBody().add(setClassField(classInfo, classSupertypeFunctionOffset,
-                    new WasmFunctionReference(supertypeFunction)));
+            var req = metadataRequirements.getInfo(classInfo.getValueType());
+            if (req != null && req.isAssignable()) {
+                var supertypeFunction = supertypeGenerator.getIsSupertypeFunction(classInfo.getValueType());
+                supertypeFunction.setReferenced(true);
+                function.getBody().add(setClassField(classInfo, classSupertypeFunctionOffset,
+                        new WasmFunctionReference(supertypeFunction)));
+            }
             function.getBody().add(setClassField(classInfo, CLASS_FIELD_OFFSET,
                     new WasmGetGlobal(classClass.pointer)));
             if (classInfo.initializerPointer != null) {
@@ -265,9 +268,11 @@ public class WasmGCClassGenerator implements WasmGCClassInfoProvider, WasmGCInit
                 default:
                     throw new IllegalArgumentException();
             }
+            var req = metadataRequirements.getInfo(type);
+            var name = req != null && req.name() ? ReflectionUtil.typeName(type.getKind()) : null;
             target.add(fillPrimitiveClass(
                     classInfo.pointer,
-                    ReflectionUtil.typeName(type.getKind()),
+                    name,
                     kind
             ));
         };
@@ -401,10 +406,13 @@ public class WasmGCClassGenerator implements WasmGCClassInfoProvider, WasmGCInit
     }
 
     private WasmExpression fillPrimitiveClass(WasmGlobal global, String name, int kind) {
+        var str = name != null
+                ? new WasmGetGlobal(strings.getStringConstant(name).global)
+                : new WasmNullConstant(standardClasses.stringClass().getType());
         return new WasmCall(
                 getCreatePrimitiveClassFunction(),
                 new WasmGetGlobal(global),
-                new WasmGetGlobal(strings.getStringConstant(name).global),
+                str,
                 new WasmInt32Constant(kind)
         );
     }
diff --git a/core/src/main/java/org/teavm/model/analysis/ClassMetadataRequirements.java b/core/src/main/java/org/teavm/model/analysis/ClassMetadataRequirements.java
index a5e56b260..037f45929 100644
--- a/core/src/main/java/org/teavm/model/analysis/ClassMetadataRequirements.java
+++ b/core/src/main/java/org/teavm/model/analysis/ClassMetadataRequirements.java
@@ -20,6 +20,7 @@ import java.util.Map;
 import org.teavm.dependency.DependencyInfo;
 import org.teavm.dependency.MethodDependencyInfo;
 import org.teavm.model.MethodReference;
+import org.teavm.model.ValueType;
 
 public class ClassMetadataRequirements {
     private static final MethodReference GET_NAME_METHOD = new MethodReference(Class.class, "getName", String.class);
@@ -27,12 +28,14 @@ public class ClassMetadataRequirements {
             "getSimpleName", String.class);
     private static final MethodReference GET_SUPERCLASS_METHOD = new MethodReference(Class.class, "getSuperclass",
             Class.class);
+    private static final MethodReference IS_ASSIGNABLE_METHOD = new MethodReference(Class.class, "isAssignableFrom",
+            Class.class, boolean.class);
     private static final MethodReference GET_DECLARING_CLASS_METHOD = new MethodReference(Class.class,
             "getDeclaringClass", Class.class);
     private static final MethodReference GET_ENCLOSING_CLASS_METHOD = new MethodReference(Class.class,
             "getEnclosingClass", Class.class);
     private static final ClassInfo EMPTY_INFO = new ClassInfo();
-    private Map<String, ClassInfo> requirements = new HashMap<>();
+    private Map<ValueType, ClassInfo> requirements = new HashMap<>();
 
     public ClassMetadataRequirements(DependencyInfo dependencyInfo) {
         MethodDependencyInfo getNameMethod = dependencyInfo.getMethod(GET_NAME_METHOD);
@@ -45,7 +48,7 @@ public class ClassMetadataRequirements {
             String[] classNames = getSimpleNameMethod.getVariable(0).getClassValueNode().getTypes();
             addClassesRequiringName(requirements, classNames);
             for (String className : classNames) {
-                ClassInfo classInfo = requirements.computeIfAbsent(className, k -> new ClassInfo());
+                ClassInfo classInfo = requirements.computeIfAbsent(decodeType(className), k -> new ClassInfo());
                 classInfo.simpleName = true;
                 classInfo.enclosingClass = true;
             }
@@ -53,9 +56,17 @@ public class ClassMetadataRequirements {
 
         var getSuperclassMethod = dependencyInfo.getMethod(GET_SUPERCLASS_METHOD);
         if (getSuperclassMethod != null) {
-            String[] classNames = getSuperclassMethod.getVariable(0).getClassValueNode().getTypes();
-            for (String className : classNames) {
-                requirements.computeIfAbsent(className, k -> new ClassInfo()).declaringClass = true;
+            var classNames = getSuperclassMethod.getVariable(0).getClassValueNode().getTypes();
+            for (var className : classNames) {
+                requirements.computeIfAbsent(decodeType(className), k -> new ClassInfo()).declaringClass = true;
+            }
+        }
+
+        var isAssignableMethod = dependencyInfo.getMethod(IS_ASSIGNABLE_METHOD);
+        if (isAssignableMethod != null) {
+            var classNames = getSuperclassMethod.getVariable(0).getClassValueNode().getTypes();
+            for (var className : classNames) {
+                requirements.computeIfAbsent(decodeType(className), k -> new ClassInfo()).isAssignable = true;
             }
         }
 
@@ -63,7 +74,7 @@ public class ClassMetadataRequirements {
         if (getDeclaringClassMethod != null) {
             String[] classNames = getDeclaringClassMethod.getVariable(0).getClassValueNode().getTypes();
             for (String className : classNames) {
-                requirements.computeIfAbsent(className, k -> new ClassInfo()).declaringClass = true;
+                requirements.computeIfAbsent(decodeType(className), k -> new ClassInfo()).declaringClass = true;
             }
         }
 
@@ -71,12 +82,16 @@ public class ClassMetadataRequirements {
         if (getEnclosingClassMethod != null) {
             String[] classNames = getEnclosingClassMethod.getVariable(0).getClassValueNode().getTypes();
             for (String className : classNames) {
-                requirements.computeIfAbsent(className, k -> new ClassInfo()).enclosingClass = true;
+                requirements.computeIfAbsent(decodeType(className), k -> new ClassInfo()).enclosingClass = true;
             }
         }
     }
 
     public Info getInfo(String className) {
+        return getInfo(ValueType.object(className));
+    }
+
+    public Info getInfo(ValueType className) {
         ClassInfo result = requirements.get(className);
         if (result == null) {
             result = EMPTY_INFO;
@@ -84,19 +99,19 @@ public class ClassMetadataRequirements {
         return result;
     }
 
-    private void addClassesRequiringName(Map<String, ClassInfo> target, String[] source) {
+    private void addClassesRequiringName(Map<ValueType, ClassInfo> target, String[] source) {
         for (String typeName : source) {
-            if (typeName.startsWith("[")) {
-                if (!typeName.endsWith(";")) {
-                    continue;
-                }
-                int index = 0;
-                while (typeName.charAt(index) == '[') {
-                    ++index;
-                }
-                typeName = typeName.substring(index, typeName.length() - 1).replace('/', '.');
-            }
-            target.computeIfAbsent(typeName, k -> new ClassInfo()).name = true;
+            target.computeIfAbsent(decodeType(typeName), k -> new ClassInfo()).name = true;
+        }
+    }
+
+    private ValueType decodeType(String typeName) {
+        if (typeName.startsWith("[")) {
+            return ValueType.parseIfPossible(typeName);
+        } else if (typeName.startsWith("~")) {
+            return ValueType.parseIfPossible(typeName.substring(1));
+        } else {
+            return ValueType.object(typeName);
         }
     }
 
@@ -106,6 +121,7 @@ public class ClassMetadataRequirements {
         boolean declaringClass;
         boolean enclosingClass;
         boolean superclass;
+        boolean isAssignable;
 
         @Override
         public boolean name() {
@@ -131,6 +147,11 @@ public class ClassMetadataRequirements {
         public boolean superclass() {
             return superclass;
         }
+
+        @Override
+        public boolean isAssignable() {
+            return isAssignable;
+        }
     }
 
     public interface Info {
@@ -143,5 +164,7 @@ public class ClassMetadataRequirements {
         boolean enclosingClass();
 
         boolean superclass();
+
+        boolean isAssignable();
     }
 }