diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/FunctionCodegen.java b/compiler/backend/src/org/jetbrains/jet/codegen/FunctionCodegen.java
index b338074012d..9b7ee1c12df 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/FunctionCodegen.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/FunctionCodegen.java
@@ -356,8 +356,6 @@ public class FunctionCodegen extends GenerationStateAware {
             }
             kotlinFlags |= DescriptorKindUtils.kindToFlags(functionDescriptor.getKind());
             //noinspection ConstantConditions
-            if (functionDescriptor.getReturnType().isNullable())
-                kotlinFlags |= JvmStdlibNames.FLAG_NULLABLE_RETURN_TYPE_BIT;
             aw.writeFlags(kotlinFlags);
             aw.writeTypeParameters(jvmSignature.getKotlinTypeParameter());
             aw.writeReturnType(jvmSignature.getKotlinReturnType());
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/ImplementationBodyCodegen.java b/compiler/backend/src/org/jetbrains/jet/codegen/ImplementationBodyCodegen.java
index daaa2764d0f..2abc342250d 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/ImplementationBodyCodegen.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/ImplementationBodyCodegen.java
@@ -1225,8 +1225,6 @@ public class ImplementationBodyCodegen extends ClassBodyCodegen {
                 else {
                     JetType returnType = fun.getReturnType();
                     assert returnType != null;
-                    if (returnType.isNullable())
-                        kotlinFlags |= JvmStdlibNames.FLAG_NULLABLE_RETURN_TYPE_BIT;
                     aw.writeTypeParameters(jvmSignature.getKotlinTypeParameter());
                     aw.writeReturnType(jvmSignature.getKotlinReturnType());
                 }
diff --git a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/JavaDescriptorResolver.java b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/JavaDescriptorResolver.java
index af204690e32..d827e475e3b 100644
--- a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/JavaDescriptorResolver.java
+++ b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/JavaDescriptorResolver.java
@@ -1879,10 +1879,8 @@ public class JavaDescriptorResolver implements DependencyClassByQualifiedNameRes
             transformedType = semanticServices.getTypeTransformer().transformToType(
                     returnType, JavaTypeTransformer.TypeUsage.MEMBER_SIGNATURE_COVARIANT, typeVariableResolver);
         }
-        if (method.getJetMethod().returnTypeNullable()) {
-            return TypeUtils.makeNullableAsSpecified(transformedType, true);
-        }
-        else if (findAnnotation(method.getPsiMethod(), JvmAbi.JETBRAINS_NOT_NULL_ANNOTATION.getFqName().getFqName()) != null) {
+
+        if (findAnnotation(method.getPsiMethod(), JvmAbi.JETBRAINS_NOT_NULL_ANNOTATION.getFqName().getFqName()) != null) {
             return TypeUtils.makeNullableAsSpecified(transformedType, false);
         }
         else {
diff --git a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/JvmStdlibNames.java b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/JvmStdlibNames.java
index b65a40c930d..f43a425aaea 100644
--- a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/JvmStdlibNames.java
+++ b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/JvmStdlibNames.java
@@ -52,14 +52,13 @@ public class JvmStdlibNames {
     public static final int FLAG_FORCE_FINAL_BIT = 1 << 2;
     public static final int FLAG_PRIVATE_BIT =  1 << 3;
     public static final int FLAG_INTERNAL_BIT = 1 << 4;
-    public static final int FLAG_NULLABLE_RETURN_TYPE_BIT = 1 << 5;
 
     // three bits (one reserved)
-    public static final int FLAG_KIND_MASK = 7 << 6;
-    public static final int FLAG_KIND_DECLARATION =   0 << 6;
-    public static final int FLAG_KIND_FAKE_OVERRIDE = 1 << 6;
-    public static final int FLAG_KIND_DELEGATION =    2 << 6;
-    public static final int FLAG_KIND_SYNTHESIZED =   3 << 6;
+    public static final int FLAG_KIND_MASK = 7 << 5;
+    public static final int FLAG_KIND_DECLARATION =   0 << 5;
+    public static final int FLAG_KIND_FAKE_OVERRIDE = 1 << 5;
+    public static final int FLAG_KIND_DELEGATION =    2 << 5;
+    public static final int FLAG_KIND_SYNTHESIZED =   3 << 5;
 
     public static final JvmClassName JET_CONSTRUCTOR = JvmClassName.byFqNameWithoutInnerClasses("jet.runtime.typeinfo.JetConstructor");
 
diff --git a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/PsiClassFinderImpl.java b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/PsiClassFinderImpl.java
index 2e24ee78af4..66da45adf44 100644
--- a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/PsiClassFinderImpl.java
+++ b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/PsiClassFinderImpl.java
@@ -79,19 +79,21 @@ public class PsiClassFinderImpl implements PsiClassFinder {
             return null;
         }
 
-        PsiAnnotation assertInvisibleAnnotation = JavaDescriptorResolver
-                .findAnnotation(original, JvmStdlibNames.ASSERT_INVISIBLE_IN_RESOLVER.getFqName().getFqName());
-        if (assertInvisibleAnnotation != null) {
-            if (runtimeClassesHandleMode == RuntimeClassesHandleMode.IGNORE) {
-                return null;
-            }
-            else if (runtimeClassesHandleMode == RuntimeClassesHandleMode.THROW) {
-                throw new IllegalStateException(
-                        "classpath is configured incorrectly:" +
-                        " class " + qualifiedName + " from runtime must not be loaded by compiler");
-            }
-            else {
-                throw new IllegalStateException("unknown parameter value: " + runtimeClassesHandleMode);
+        if ("jet".equals(qualifiedName.parent().getFqName())) {
+            PsiAnnotation assertInvisibleAnnotation = JavaDescriptorResolver
+                    .findAnnotation(original, JvmStdlibNames.ASSERT_INVISIBLE_IN_RESOLVER.getFqName().getFqName());
+            if (assertInvisibleAnnotation != null) {
+                if (runtimeClassesHandleMode == RuntimeClassesHandleMode.IGNORE) {
+                    return null;
+                }
+                else if (runtimeClassesHandleMode == RuntimeClassesHandleMode.THROW) {
+                    throw new IllegalStateException(
+                            "classpath is configured incorrectly:" +
+                            " class " + qualifiedName + " from runtime must not be loaded by compiler");
+                }
+                else {
+                    throw new IllegalStateException("unknown parameter value: " + runtimeClassesHandleMode);
+                }
             }
         }
 
diff --git a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/kt/JetMethodAnnotation.java b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/kt/JetMethodAnnotation.java
index fb6f2236323..7873af880c1 100644
--- a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/kt/JetMethodAnnotation.java
+++ b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/kt/JetMethodAnnotation.java
@@ -61,10 +61,6 @@ public class JetMethodAnnotation extends PsiAnnotationWithFlags {
         return returnType;
     }
 
-    public boolean returnTypeNullable() {
-        return (flags() & JvmStdlibNames.FLAG_NULLABLE_RETURN_TYPE_BIT) != 0;
-    }
-
     @NotNull
     public String propertyType() {
         checkInitialized();