diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/FunctionCodegen.java b/compiler/backend/src/org/jetbrains/jet/codegen/FunctionCodegen.java
index 834c6dbbe83..ea691936476 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/FunctionCodegen.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/FunctionCodegen.java
@@ -57,7 +57,6 @@ import static org.jetbrains.jet.codegen.CodegenUtil.*;
 import static org.jetbrains.jet.codegen.binding.CodegenBinding.isLocalFun;
 import static org.jetbrains.jet.lang.resolve.BindingContextUtils.callableDescriptorToDeclaration;
 import static org.jetbrains.jet.lang.resolve.BindingContextUtils.descriptorToDeclaration;
-import static org.jetbrains.jet.lang.resolve.java.AsmTypeConstants.JAVA_ARRAY_GENERIC_TYPE;
 import static org.jetbrains.jet.lang.resolve.java.AsmTypeConstants.OBJECT_TYPE;
 
 /**
@@ -772,20 +771,13 @@ public class FunctionCodegen extends GenerationStateAware {
 
             Type[] argTypes = overridden.getArgumentTypes();
             Type[] originalArgTypes = jvmSignature.getArgumentTypes();
+
             InstructionAdapter iv = new InstructionAdapter(mv);
             iv.load(0, OBJECT_TYPE);
             for (int i = 0, reg = 1; i < argTypes.length; i++) {
-                Type argType = argTypes[i];
-                iv.load(reg, argType);
-                if (argType.getSort() == Type.OBJECT) {
-                    StackValue.onStack(OBJECT_TYPE).put(originalArgTypes[i], iv);
-                }
-                else if (argType.getSort() == Type.ARRAY) {
-                    StackValue.onStack(JAVA_ARRAY_GENERIC_TYPE).put(originalArgTypes[i], iv);
-                }
-
+                StackValue.local(reg, argTypes[i]).put(originalArgTypes[i], iv);
                 //noinspection AssignmentToForLoopParameter
-                reg += argType.getSize();
+                reg += argTypes[i].getSize();
             }
 
             iv.invokevirtual(state.getTypeMapper().mapType(
@@ -828,22 +820,16 @@ public class FunctionCodegen extends GenerationStateAware {
         else if (state.getClassBuilderMode() == ClassBuilderMode.FULL) {
             mv.visitCode();
 
-            Type[] argTypes = overriddenMethod.getArgumentTypes();
+            Type[] argTypes = delegateMethod.getArgumentTypes();
+            Type[] originalArgTypes = overriddenMethod.getArgumentTypes();
+
             InstructionAdapter iv = new InstructionAdapter(mv);
             iv.load(0, OBJECT_TYPE);
             field.put(field.type, iv);
             for (int i = 0, reg = 1; i < argTypes.length; i++) {
-                Type argType = argTypes[i];
-                iv.load(reg, argType);
-                if (argType.getSort() == Type.OBJECT) {
-                    StackValue.onStack(OBJECT_TYPE).put(overriddenMethod.getArgumentTypes()[i], iv);
-                }
-                else if (argType.getSort() == Type.ARRAY) {
-                    StackValue.onStack(JAVA_ARRAY_GENERIC_TYPE).put(overriddenMethod.getArgumentTypes()[i], iv);
-                }
-
+                StackValue.local(reg, argTypes[i]).put(originalArgTypes[i], iv);
                 //noinspection AssignmentToForLoopParameter
-                reg += argType.getSize();
+                reg += argTypes[i].getSize();
             }
 
             ClassDescriptor classDescriptor = (ClassDescriptor) overriddenDescriptor.getContainingDeclaration();
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/ImplementationBodyCodegen.java b/compiler/backend/src/org/jetbrains/jet/codegen/ImplementationBodyCodegen.java
index 26a482ee292..d821de5eee4 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/ImplementationBodyCodegen.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/ImplementationBodyCodegen.java
@@ -1273,14 +1273,13 @@ public class ImplementationBodyCodegen extends ClassBodyCodegen {
 
                     Type[] argTypes = function.getArgumentTypes();
                     List<Type> originalArgTypes = jvmSignature.getValueParameterTypes();
+
                     InstructionAdapter iv = new InstructionAdapter(mv);
                     iv.load(0, OBJECT_TYPE);
                     for (int i = 0, reg = 1; i < argTypes.length; i++) {
-                        Type argType = argTypes[i];
-                        iv.load(reg, argType);
-                        StackValue.coerce(argType, originalArgTypes.get(i), iv);
+                        StackValue.local(reg, argTypes[i]).put(originalArgTypes.get(i), iv);
                         //noinspection AssignmentToForLoopParameter
-                        reg += argType.getSize();
+                        reg += argTypes[i].getSize();
                     }
 
                     JetType jetType = CodegenUtil.getSuperClass(declaration);
diff --git a/compiler/testData/codegen/classes/delegationGenericArg.kt b/compiler/testData/codegen/classes/delegationGenericArg.kt
new file mode 100644
index 00000000000..fed9f214dd8
--- /dev/null
+++ b/compiler/testData/codegen/classes/delegationGenericArg.kt
@@ -0,0 +1,12 @@
+trait A<T> {
+    fun foo(t: T): String
+}
+
+class Derived(a: A<Int>) : A<Int> by a
+
+fun box(): String {
+    val o = object : A<Int> {
+        override fun foo(t: Int) = if (t == 42) "OK" else "Fail $t"
+    }
+    return Derived(o).foo(42)
+}
diff --git a/compiler/testData/codegen/classes/delegationGenericArgUpperBound.kt b/compiler/testData/codegen/classes/delegationGenericArgUpperBound.kt
new file mode 100644
index 00000000000..b5da8aaffee
--- /dev/null
+++ b/compiler/testData/codegen/classes/delegationGenericArgUpperBound.kt
@@ -0,0 +1,12 @@
+trait A<T: Number> {
+    fun foo(t: T): String
+}
+
+class Derived(a: A<Int>) : A<Int> by a
+
+fun box(): String {
+    val o = object : A<Int> {
+        override fun foo(t: Int) = if (t == 42) "OK" else "Fail $t"
+    }
+    return Derived(o).foo(42)
+}
diff --git a/compiler/testData/codegen/classes/delegationGenericLongArg.kt b/compiler/testData/codegen/classes/delegationGenericLongArg.kt
new file mode 100644
index 00000000000..df80d1064e6
--- /dev/null
+++ b/compiler/testData/codegen/classes/delegationGenericLongArg.kt
@@ -0,0 +1,12 @@
+trait A<T, U> {
+    fun foo(t: T, u: U): String
+}
+
+class Derived(a: A<Long, Int>) : A<Long, Int> by a
+
+fun box(): String {
+    val o = object : A<Long, Int> {
+        override fun foo(t: Long, u: Int) = if (t == u.toLong()) "OK" else "Fail $t $u"
+    }
+    return Derived(o).foo(42, 42)
+}
diff --git a/compiler/tests/org/jetbrains/jet/codegen/ClassGenTest.java b/compiler/tests/org/jetbrains/jet/codegen/ClassGenTest.java
index 104fb5f3fd9..999f8088b3b 100644
--- a/compiler/tests/org/jetbrains/jet/codegen/ClassGenTest.java
+++ b/compiler/tests/org/jetbrains/jet/codegen/ClassGenTest.java
@@ -120,6 +120,21 @@ public class ClassGenTest extends CodegenTestCase {
         blackBoxFile("classes/delegationMethodsWithArgs.kt");
     }
 
+    public void testDelegationGenericArg() {
+        createEnvironmentWithMockJdkAndIdeaAnnotations(ConfigurationKind.JDK_ONLY);
+        blackBoxFile("classes/delegationGenericArg.kt");
+    }
+
+    public void testDelegationGenericLongArg() {
+        createEnvironmentWithMockJdkAndIdeaAnnotations(ConfigurationKind.JDK_ONLY);
+        blackBoxFile("classes/delegationGenericLongArg.kt");
+    }
+
+    public void testDelegationGenericArgUpperBound() {
+        createEnvironmentWithMockJdkAndIdeaAnnotations(ConfigurationKind.JDK_ONLY);
+        blackBoxFile("classes/delegationGenericArgUpperBound.kt");
+    }
+
     public void testFunDelegation() throws Exception {
         createEnvironmentWithMockJdkAndIdeaAnnotations(ConfigurationKind.JDK_ONLY);
         blackBoxFile("classes/funDelegation.jet");