diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetPsiUtil.java b/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetPsiUtil.java
index 2d130fa4faa..cb9fa86166f 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetPsiUtil.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetPsiUtil.java
@@ -158,13 +158,14 @@ public class JetPsiUtil {
         }
     }
 
-    public static FqName getFQName(JetFile file) {
+    @NotNull
+    public static FqName getFQName(@NotNull JetFile file) {
         JetNamespaceHeader header = file.getNamespaceHeader();
         return header != null ? header.getFqName() : FqName.ROOT;
     }
 
     @Nullable
-    public static FqName getFQName(JetNamedDeclaration namedDeclaration) {
+    public static FqName getFQName(@NotNull JetNamedDeclaration namedDeclaration) {
         if (namedDeclaration instanceof JetObjectDeclarationName) {
             JetNamedDeclaration objectDeclaration = PsiTreeUtil.getParentOfType(namedDeclaration, JetObjectDeclaration.class);
             if (objectDeclaration == null) {
@@ -233,7 +234,7 @@ public class JetPsiUtil {
     }
 
     @Nullable
-    public static Name getShortName(JetAnnotationEntry annotation) {
+    public static Name getShortName(@NotNull JetAnnotationEntry annotation) {
         JetTypeReference typeReference = annotation.getTypeReference();
         assert typeReference != null : "Annotation entry hasn't typeReference " + annotation.getText();
         JetTypeElement typeElement = typeReference.getTypeElement();
@@ -247,7 +248,7 @@ public class JetPsiUtil {
         return null;
     }
 
-    public static boolean isDeprecated(JetModifierListOwner owner) {
+    public static boolean isDeprecated(@NotNull JetModifierListOwner owner) {
         JetModifierList modifierList = owner.getModifierList();
         if (modifierList != null) {
             List<JetAnnotationEntry> annotationEntries = modifierList.getAnnotationEntries();
@@ -263,7 +264,7 @@ public class JetPsiUtil {
 
     @Nullable
     @IfNotParsed
-    public static ImportPath getImportPath(JetImportDirective importDirective) {
+    public static ImportPath getImportPath(@NotNull JetImportDirective importDirective) {
         if (PsiTreeUtil.hasErrorElements(importDirective)) {
             return null;
         }
@@ -410,7 +411,7 @@ public class JetPsiUtil {
         return callOperationNode != null && callOperationNode.getElementType() == JetTokens.SAFE_ACCESS;
     }
 
-    public static boolean isFunctionLiteralWithoutDeclaredParameterTypes(JetExpression expression) {
+    public static boolean isFunctionLiteralWithoutDeclaredParameterTypes(@Nullable JetExpression expression) {
         if (!(expression instanceof JetFunctionLiteralExpression)) return false;
         JetFunctionLiteralExpression functionLiteral = (JetFunctionLiteralExpression) expression;
         for (JetParameter parameter : functionLiteral.getValueParameters()) {
@@ -462,6 +463,7 @@ public class JetPsiUtil {
         return null;
     }
 
+    @Nullable
     public static PsiElement getTopmostParentOfTypes(@Nullable PsiElement element, @NotNull Class<? extends PsiElement>... parentTypes) {
         if (element == null) {
             return null;
@@ -568,6 +570,7 @@ public class JetPsiUtil {
         }
     }
 
+    @Nullable
     private static IElementType getOperation(@NotNull JetExpression expression) {
         if (expression instanceof JetQualifiedExpression) {
             return ((JetQualifiedExpression) expression).getOperationSign();
@@ -683,6 +686,7 @@ public class JetPsiUtil {
         return false;
     }
 
+    @NotNull
     public static <C extends Collection<JetVariableDeclaration>> C getBlockVariableDeclarations(@NotNull JetBlockExpression block, @NotNull C collection) {
         for (JetElement element : block.getStatements()) {
             if (element instanceof JetVariableDeclaration) {
@@ -693,7 +697,7 @@ public class JetPsiUtil {
         return collection;
     }
 
-    public static boolean checkWhenExpressionHasSingleElse(JetWhenExpression whenExpression) {
+    public static boolean checkWhenExpressionHasSingleElse(@NotNull JetWhenExpression whenExpression) {
         int elseCount = 0;
         for (JetWhenEntry entry : whenExpression.getEntries()) {
             if (entry.isElse()) {
@@ -703,7 +707,8 @@ public class JetPsiUtil {
         return (elseCount == 1);
     }
 
-    public static PsiElement skipTrailingWhitespacesAndComments(PsiElement element)  {
+    @Nullable
+    public static PsiElement skipTrailingWhitespacesAndComments(@Nullable PsiElement element)  {
         return PsiTreeUtil.skipSiblingsForward(element, PsiWhiteSpace.class, PsiComment.class);
     }