diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/AbstractJumpInstruction.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/AbstractJumpInstruction.java
index 16cfcca96fe..a37d8f3ad2c 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/AbstractJumpInstruction.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/AbstractJumpInstruction.java
@@ -54,6 +54,7 @@ public abstract class AbstractJumpInstruction extends InstructionImpl {
         return updateCopyInfo(createCopy(newLabel));
     }
 
+    @NotNull
     @Override
     protected Instruction createCopy() {
         return createCopy(targetLabel);
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/Instruction.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/Instruction.java
index 232adc96b49..691129c3b8c 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/Instruction.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/Instruction.java
@@ -32,7 +32,7 @@ public interface Instruction {
     @NotNull
     Collection<Instruction> getNextInstructions();
 
-    void accept(InstructionVisitor visitor);
+    void accept(@NotNull InstructionVisitor visitor);
 
     @NotNull
     Collection<Instruction> getCopies();
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/InstructionImpl.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/InstructionImpl.java
index 0d9038697aa..f14cfdddbae 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/InstructionImpl.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/InstructionImpl.java
@@ -71,6 +71,7 @@ public abstract class InstructionImpl implements Instruction {
         return updateCopyInfo(createCopy());
     }
 
+    @NotNull
     protected abstract Instruction createCopy();
 
     @NotNull
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/JetElementInstructionImpl.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/JetElementInstructionImpl.java
index e16ac7fefdd..efa4573db75 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/JetElementInstructionImpl.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/JetElementInstructionImpl.java
@@ -20,6 +20,7 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.lang.psi.JetElement;
 
 public abstract class JetElementInstructionImpl extends InstructionImpl implements JetElementInstruction {
+    @NotNull
     protected final JetElement element;
 
     public JetElementInstructionImpl(@NotNull JetElement element) {
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/LoadUnitValueInstruction.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/LoadUnitValueInstruction.java
index e59398f2b12..278d8e3ef39 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/LoadUnitValueInstruction.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/LoadUnitValueInstruction.java
@@ -35,6 +35,7 @@ public class LoadUnitValueInstruction extends InstructionWithNext {
         return "read (Unit)";
     }
 
+    @NotNull
     @Override
     protected Instruction createCopy() {
         return new LoadUnitValueInstruction((JetExpression) element);
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/LocalFunctionDeclarationInstruction.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/LocalFunctionDeclarationInstruction.java
index 5ce9209a1de..0a9ae9a625a 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/LocalFunctionDeclarationInstruction.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/LocalFunctionDeclarationInstruction.java
@@ -62,6 +62,7 @@ public class LocalFunctionDeclarationInstruction extends InstructionWithNext {
         return "d" + "(" + element.getText() + ")";
     }
 
+    @NotNull
     @Override
     protected Instruction createCopy() {
         return new LocalFunctionDeclarationInstruction(element, body);
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/NondeterministicJumpInstruction.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/NondeterministicJumpInstruction.java
index d1ea7e79cb7..12c6f93a82f 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/NondeterministicJumpInstruction.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/NondeterministicJumpInstruction.java
@@ -85,6 +85,7 @@ public class NondeterministicJumpInstruction extends InstructionImpl{
         return sb.toString();
     }
 
+    @NotNull
     @Override
     protected Instruction createCopy() {
         return createCopy(getTargetLabels());
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/ReadValueInstruction.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/ReadValueInstruction.java
index 5d53c78d8d1..7724d8dec77 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/ReadValueInstruction.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/ReadValueInstruction.java
@@ -35,6 +35,7 @@ public class ReadValueInstruction extends InstructionWithNext {
         return "r(" + element.getText() + ")";
     }
 
+    @NotNull
     @Override
     protected Instruction createCopy() {
         return new ReadValueInstruction(element);
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/SubroutineEnterInstruction.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/SubroutineEnterInstruction.java
index d5ded806bee..03dbf34f1b0 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/SubroutineEnterInstruction.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/SubroutineEnterInstruction.java
@@ -41,6 +41,7 @@ public class SubroutineEnterInstruction extends InstructionWithNext {
         return "<START>";
     }
 
+    @NotNull
     @Override
     protected Instruction createCopy() {
         return new SubroutineEnterInstruction(subroutine);
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/SubroutineExitInstruction.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/SubroutineExitInstruction.java
index 395363fd908..076939093d2 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/SubroutineExitInstruction.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/SubroutineExitInstruction.java
@@ -57,6 +57,7 @@ public class SubroutineExitInstruction extends InstructionImpl {
         return debugLabel;
     }
 
+    @NotNull
     @Override
     protected Instruction createCopy() {
         return new SubroutineExitInstruction(subroutine, debugLabel);
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/SubroutineSinkInstruction.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/SubroutineSinkInstruction.java
index 8e16339c34b..d56bd8f0f42 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/SubroutineSinkInstruction.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/SubroutineSinkInstruction.java
@@ -51,6 +51,7 @@ public class SubroutineSinkInstruction extends InstructionImpl {
         return debugLabel;
     }
 
+    @NotNull
     @Override
     protected Instruction createCopy() {
         return new SubroutineSinkInstruction(subroutine, debugLabel);
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/UnsupportedElementInstruction.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/UnsupportedElementInstruction.java
index 73c3a8aa9d3..c3fc7b8824d 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/UnsupportedElementInstruction.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/UnsupportedElementInstruction.java
@@ -35,6 +35,7 @@ public class UnsupportedElementInstruction extends InstructionWithNext {
         return "unsupported(" + element + " : " + element.getText() + ")";
     }
 
+    @NotNull
     @Override
     protected Instruction createCopy() {
         return new UnsupportedElementInstruction(element);
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/VariableDeclarationInstruction.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/VariableDeclarationInstruction.java
index 3efa43932d7..2ad143591b1 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/VariableDeclarationInstruction.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/VariableDeclarationInstruction.java
@@ -45,6 +45,7 @@ public class VariableDeclarationInstruction extends InstructionWithNext {
         return "v(" + element.getText() + ")";
     }
 
+    @NotNull
     @Override
     protected Instruction createCopy() {
         if (element instanceof JetParameter) {
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/WriteValueInstruction.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/WriteValueInstruction.java
index 4214ca9adc4..9c8a09a5bba 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/WriteValueInstruction.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/WriteValueInstruction.java
@@ -35,7 +35,7 @@ public class WriteValueInstruction extends InstructionWithNext {
     }
 
     @Override
-    public void accept(InstructionVisitor visitor) {
+    public void accept(@NotNull InstructionVisitor visitor) {
         visitor.visitWriteValue(this);
     }
 
@@ -48,6 +48,7 @@ public class WriteValueInstruction extends InstructionWithNext {
         return "w(" + lValue.getText() + ")";
     }
 
+    @NotNull
     @Override
     protected Instruction createCopy() {
         return new WriteValueInstruction(element, lValue);