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 909017701..f715944e9 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
@@ -247,7 +247,7 @@ public class TObject {
         } else {
             RuntimeArray array = (RuntimeArray) self;
             copy = Allocator.allocateArray(cls, array.size).toStructure();
-            int itemSize = (cls.itemType.flags & RuntimeClass.PRIMITIVE) == 0 ? 4 : cls.itemType.size;
+            int itemSize = (cls.itemType.flags & RuntimeClass.PRIMITIVE) == 0 ? Address.sizeOf() : cls.itemType.size;
             Address headerSize = Address.align(Address.fromInt(Structure.sizeOf(RuntimeArray.class)), itemSize);
             size = itemSize * array.size + headerSize.toInt();
         }
diff --git a/core/src/main/java/org/teavm/backend/c/generate/ClassGenerator.java b/core/src/main/java/org/teavm/backend/c/generate/ClassGenerator.java
index f9053e076..67fdbcff6 100644
--- a/core/src/main/java/org/teavm/backend/c/generate/ClassGenerator.java
+++ b/core/src/main/java/org/teavm/backend/c/generate/ClassGenerator.java
@@ -772,7 +772,7 @@ public class ClassGenerator {
         for (int i = 1; i < ranges.size(); ++i) {
             lower = ranges.get(i - 1).upper;
             upper = ranges.get(i).lower;
-            isSupertypeWriter.println("if (tag >= " + lower + " || tag < " + upper + ") return INT32_C(0);");
+            isSupertypeWriter.println("if (tag >= " + lower + " && tag < " + upper + ") return INT32_C(0);");
         }
 
         isSupertypeWriter.println("return INT32_C(1);");
diff --git a/core/src/main/java/org/teavm/backend/c/generate/CodeGenerationVisitor.java b/core/src/main/java/org/teavm/backend/c/generate/CodeGenerationVisitor.java
index 04e0fae56..e989af519 100644
--- a/core/src/main/java/org/teavm/backend/c/generate/CodeGenerationVisitor.java
+++ b/core/src/main/java/org/teavm/backend/c/generate/CodeGenerationVisitor.java
@@ -66,6 +66,7 @@ import org.teavm.model.ClassReader;
 import org.teavm.model.MethodReader;
 import org.teavm.model.MethodReference;
 import org.teavm.model.ValueType;
+import org.teavm.model.classes.VirtualTable;
 import org.teavm.runtime.Allocator;
 import org.teavm.runtime.ExceptionHandling;
 import org.teavm.runtime.RuntimeClass;
@@ -140,6 +141,28 @@ public class CodeGenerationVisitor implements ExprVisitor, StatementVisitor {
                 return;
             }
 
+            case MODULO: {
+                switch (expr.getType()) {
+                    case FLOAT:
+                        writer.print("fmodf(");
+                        expr.getFirstOperand().acceptVisitor(this);
+                        writer.print(", ");
+                        expr.getSecondOperand().acceptVisitor(this);
+                        writer.print(")");
+                        return;
+                    case DOUBLE:
+                        writer.print("fmod(");
+                        expr.getFirstOperand().acceptVisitor(this);
+                        writer.print(", ");
+                        expr.getSecondOperand().acceptVisitor(this);
+                        writer.print(")");
+                        return;
+                    default:
+                        break;
+                }
+                break;
+            }
+
             default:
                 break;
         }
@@ -372,28 +395,47 @@ public class CodeGenerationVisitor implements ExprVisitor, StatementVisitor {
                 break;
             }
             case DYNAMIC: {
-                String receiver = "recv_" + temporaryReceiverLevel++;
-                maxTemporaryReceiverLevel = Math.max(maxTemporaryReceiverLevel, temporaryReceiverLevel);
-                writer.print("((").print(receiver).print(" = ");
-                expr.getArguments().get(0).acceptVisitor(this);
+                VirtualTable vtable = context.getVirtualTableProvider().lookup(expr.getMethod().getClassName());
+                if (vtable == null || !vtable.getEntries().containsKey(expr.getMethod().getDescriptor())) {
+                    writer.print("(");
+                    for (Expr arg : expr.getArguments()) {
+                        arg.acceptVisitor(this);
+                        writer.print(", ");
+                    }
+                    printDefaultValue(expr.getMethod().getReturnType());
+                    writer.print(")");
+                } else {
+                    String receiver = "recv_" + temporaryReceiverLevel++;
+                    maxTemporaryReceiverLevel = Math.max(maxTemporaryReceiverLevel, temporaryReceiverLevel);
+                    writer.print("((").print(receiver).print(" = ");
+                    expr.getArguments().get(0).acceptVisitor(this);
 
-                writer.print("), METHOD(")
-                        .print(receiver).print(", ")
-                        .print(names.forClassClass(expr.getMethod().getClassName())).print(", ")
-                        .print(names.forVirtualMethod(expr.getMethod()))
-                        .print(")(").print(receiver);
-                for (int i = 1; i < expr.getArguments().size(); ++i) {
-                    writer.print(", ");
-                    expr.getArguments().get(i).acceptVisitor(this);
+                    writer.print("), METHOD(")
+                            .print(receiver).print(", ")
+                            .print(names.forClassClass(expr.getMethod().getClassName())).print(", ")
+                            .print(names.forVirtualMethod(expr.getMethod()))
+                            .print(")(").print(receiver);
+                    for (int i = 1; i < expr.getArguments().size(); ++i) {
+                        writer.print(", ");
+                        expr.getArguments().get(i).acceptVisitor(this);
+                    }
+                    writer.print("))");
+
+                    temporaryReceiverLevel--;
                 }
-                writer.print("))");
-
-                temporaryReceiverLevel--;
                 break;
             }
         }
     }
 
+    private void printDefaultValue(ValueType type) {
+        if (type instanceof ValueType.Primitive) {
+            writer.print("0");
+        } else {
+            writer.print("NULL");
+        }
+    }
+
     private void processInclude(AnnotationContainerReader container) {
         AnnotationReader annot = container.get(Include.class.getName());
         if (annot == null) {
diff --git a/tests/src/test/java/org/teavm/classlib/java/util/VectorTest.java b/tests/src/test/java/org/teavm/classlib/java/util/VectorTest.java
index 626b86a74..255e5b6ed 100644
--- a/tests/src/test/java/org/teavm/classlib/java/util/VectorTest.java
+++ b/tests/src/test/java/org/teavm/classlib/java/util/VectorTest.java
@@ -52,6 +52,7 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 import java.util.Arrays;
@@ -326,9 +327,11 @@ public class VectorTest {
         Enumeration<Object> orgNum = tVector.elements();
         Enumeration<Object> cnum = v.elements();
 
+        int index = 0;
         while (orgNum.hasMoreElements()) {
             assertTrue("Not enough elements copied", cnum.hasMoreElements());
-            assertTrue("Vector cloned improperly, elements do not match", orgNum.nextElement() == cnum.nextElement());
+            assertSame("Vector cloned improperly, element " + index++ + " does not match",
+                    orgNum.nextElement(), cnum.nextElement());
         }
         assertTrue("Not enough elements copied", !cnum.hasMoreElements());
     }