diff --git a/idea/src/org/jetbrains/jet/codegen/ExpressionCodegen.java b/idea/src/org/jetbrains/jet/codegen/ExpressionCodegen.java
index 0fb9ca4fa47..8b01275db4b 100644
--- a/idea/src/org/jetbrains/jet/codegen/ExpressionCodegen.java
+++ b/idea/src/org/jetbrains/jet/codegen/ExpressionCodegen.java
@@ -7,7 +7,6 @@ import com.intellij.psi.tree.IElementType;
 import com.intellij.psi.util.PsiTreeUtil;
 import jet.IntRange;
 import jet.JetObject;
-import jet.NoPatternMatchedException;
 import jet.Range;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.lang.descriptors.*;
@@ -44,6 +43,7 @@ public class ExpressionCodegen extends JetVisitor {
     private static final String CLASS_RANGE = "jet/Range";
     private static final String CLASS_INT_RANGE = "jet/IntRange";
     private static final String CLASS_NO_PATTERN_MATCHED_EXCEPTION = "jet/NoPatternMatchedException";
+    private static final String CLASS_TYPE_CAST_EXCEPTION = "jet/TypeCastException";
 
     private static final String ITERABLE_ITERATOR_DESCRIPTOR = "()Ljava/util/Iterator;";
     private static final String ITERATOR_HASNEXT_DESCRIPTOR = "()Z";
@@ -58,7 +58,6 @@ public class ExpressionCodegen extends JetVisitor {
     private static final Type RANGE_TYPE = Type.getType(Range.class);
     private static final Type INT_RANGE_TYPE = Type.getType(IntRange.class);
     private static final Type JET_OBJECT_TYPE = Type.getType(JetObject.class);
-    private static final Type NO_PATTERN_MATCHED_EXCEPTION_TYPE = Type.getType(NoPatternMatchedException.class);
 
     private final Stack<Label> myContinueTargets = new Stack<Label>();
     private final Stack<Label> myBreakTargets = new Stack<Label>();
@@ -1506,23 +1505,23 @@ public class ExpressionCodegen extends JetVisitor {
             }
             Type type = typeMapper.mapType(jetType, OwnerKind.INTERFACE);
             gen(expression.getLeft(), OBJECT_TYPE);
+            generateInstanceOf(new Runnable() {
+                        @Override
+                        public void run() {
+                            gen(expression.getLeft(), OBJECT_TYPE);
+                        }
+                    }, jetType, true);
+            Label isInstance = new Label();
+            v.ifne(isInstance);
+            v.pop();
             if (opToken == JetTokens.AS_SAFE) {
-                generateInstanceOf(new Runnable() {
-                            @Override
-                            public void run() {
-                                gen(expression.getLeft(), OBJECT_TYPE);
-                            }
-                        }, jetType, true);
-                Label isInstance = new Label();
-                v.ifne(isInstance);
-                v.pop();
                 v.aconst(null);
-                v.mark(isInstance);
-                myStack.push(StackValue.onStack(type));
             }
             else {
-                throw new UnsupportedOperationException("'as' not yet implemented");
+                throwNewException(CLASS_TYPE_CAST_EXCEPTION);
             }
+            v.mark(isInstance);
+            myStack.push(StackValue.onStack(type));
         }
     }
 
@@ -1671,10 +1670,7 @@ public class ExpressionCodegen extends JetVisitor {
         }
         if (!hasElse && nextEntry != null) {
             v.mark(nextEntry);
-            v.anew(NO_PATTERN_MATCHED_EXCEPTION_TYPE);
-            v.dup();
-            v.invokespecial(CLASS_NO_PATTERN_MATCHED_EXCEPTION, "<init>", "()V");
-            v.athrow();
+            throwNewException(CLASS_NO_PATTERN_MATCHED_EXCEPTION);
         }
         v.mark(end);
         final Type type = expressionType(expression);
@@ -1685,6 +1681,13 @@ public class ExpressionCodegen extends JetVisitor {
         myMap.leaveTemp(subjectType.getSize());
     }
 
+    private void throwNewException(final String className) {
+        v.anew(Type.getObjectType(className));
+        v.dup();
+        v.invokespecial(className, "<init>", "()V");
+        v.athrow();
+    }
+
     private static class CompilationException extends RuntimeException {
         private CompilationException() {
         }
diff --git a/idea/tests/org/jetbrains/jet/codegen/TypeInfoTest.java b/idea/tests/org/jetbrains/jet/codegen/TypeInfoTest.java
index b34f95aaef1..02b8d92fe07 100644
--- a/idea/tests/org/jetbrains/jet/codegen/TypeInfoTest.java
+++ b/idea/tests/org/jetbrains/jet/codegen/TypeInfoTest.java
@@ -1,6 +1,7 @@
 package org.jetbrains.jet.codegen;
 
 import jet.JetObject;
+import jet.TypeCastException;
 import jet.typeinfo.TypeInfo;
 
 import java.lang.reflect.Method;
@@ -31,13 +32,20 @@ public class TypeInfoTest extends CodegenTestCase {
 
     public void testAsSafeOperator() throws Exception {
         loadText("fun foo(x: Any) = x as? Runnable");
-        System.out.println(generateToText());
         Method foo = generateFunction();
         assertNull(foo.invoke(null, new Object()));
         Runnable r = newRunnable();
         assertSame(r, foo.invoke(null, r));
     }
 
+    public void testAsOperator() throws Exception {
+        loadText("fun foo(x: Any) = x as Runnable");
+        Method foo = generateFunction();
+        Runnable r = newRunnable();
+        assertSame(r, foo.invoke(null, r));
+        assertThrows(foo, TypeCastException.class, null, new Object());
+    }
+
     public void testIsOperator() throws Exception {
         loadText("fun foo(x: Any) = x is Runnable");
         Method foo = generateFunction();
diff --git a/stdlib/src/jet/TypeCastException.java b/stdlib/src/jet/TypeCastException.java
new file mode 100644
index 00000000000..60199224f25
--- /dev/null
+++ b/stdlib/src/jet/TypeCastException.java
@@ -0,0 +1,7 @@
+package jet;
+
+/**
+ * @author yole
+ */
+public class TypeCastException extends ClassCastException {
+}