diff --git a/compiler/cli/src/org/jetbrains/jet/cli/jvm/compiler/CliVirtualFileFinder.java b/compiler/cli/src/org/jetbrains/jet/cli/jvm/compiler/CliVirtualFileFinder.java
index 7be8112f25e..ca45bdbf7af 100644
--- a/compiler/cli/src/org/jetbrains/jet/cli/jvm/compiler/CliVirtualFileFinder.java
+++ b/compiler/cli/src/org/jetbrains/jet/cli/jvm/compiler/CliVirtualFileFinder.java
@@ -79,7 +79,7 @@ public class CliVirtualFileFinder implements VirtualFileFinder {
                 return null;
             }
             //NOTE: currently we use VirtualFileFinder to find Kotlin binaries only
-            if (KotlinClassFileHeader.readKotlinHeaderFromClassFile(vFile).getType() != null) {
+            if (KotlinClassFileHeader.readKotlinHeaderFromClassFile(vFile) != null) {
                 return vFile;
             }
         }
diff --git a/core/descriptor.loader.java/src/org/jetbrains/jet/lang/resolve/java/resolver/DeserializedDescriptorResolver.java b/core/descriptor.loader.java/src/org/jetbrains/jet/lang/resolve/java/resolver/DeserializedDescriptorResolver.java
index 6258ffa260b..edd797e2dc0 100644
--- a/core/descriptor.loader.java/src/org/jetbrains/jet/lang/resolve/java/resolver/DeserializedDescriptorResolver.java
+++ b/core/descriptor.loader.java/src/org/jetbrains/jet/lang/resolve/java/resolver/DeserializedDescriptorResolver.java
@@ -126,8 +126,11 @@ public final class DeserializedDescriptorResolver {
     @Nullable
     private String[] readData(@NotNull VirtualFile virtualFile) {
         KotlinClassFileHeader header = KotlinClassFileHeader.readKotlinHeaderFromClassFile(virtualFile);
+        if (header == null) {
+            return null;
+        }
         int version = header.getVersion();
-        if (!isAbiVersionCompatible(version) && header.getType() != null) {
+        if (!isAbiVersionCompatible(version)) {
             errorReporter.reportIncompatibleAbiVersion(header.getFqName(), virtualFile, version);
             return null;
         }
diff --git a/core/descriptor.loader.java/src/org/jetbrains/jet/lang/resolve/java/resolver/KotlinClassFileHeader.java b/core/descriptor.loader.java/src/org/jetbrains/jet/lang/resolve/java/resolver/KotlinClassFileHeader.java
index 6f763a8ff54..028505d9a1c 100644
--- a/core/descriptor.loader.java/src/org/jetbrains/jet/lang/resolve/java/resolver/KotlinClassFileHeader.java
+++ b/core/descriptor.loader.java/src/org/jetbrains/jet/lang/resolve/java/resolver/KotlinClassFileHeader.java
@@ -23,12 +23,19 @@ import static org.jetbrains.jet.lang.resolve.java.AbiVersionUtil.isAbiVersionCom
 public final class KotlinClassFileHeader {
     private static final Logger LOG = Logger.getInstance(KotlinClassFileHeader.class);
 
-    @NotNull
+    @Nullable
     public static KotlinClassFileHeader readKotlinHeaderFromClassFile(@NotNull VirtualFile virtualFile) {
         try {
             ClassReader reader = new ClassReader(virtualFile.contentsToByteArray());
             ReadDataFromAnnotationVisitor visitor = new ReadDataFromAnnotationVisitor();
             reader.accept(visitor, SKIP_CODE | SKIP_FRAMES | SKIP_DEBUG);
+            if (visitor.type == null) {
+                return null;
+            }
+            if (visitor.fqName == null) {
+                LOG.error("File doesn't have a class name: " + virtualFile);
+                return null;
+            }
             return new KotlinClassFileHeader(visitor.version, visitor.annotationData, visitor.type, visitor.fqName);
         }
         catch (IOException e) {
@@ -70,14 +77,11 @@ public final class KotlinClassFileHeader {
     }
 
     private final int version;
-    @Nullable
     private final String[] annotationData;
-    @Nullable
     private final HeaderType type;
-    @Nullable
     private final FqName fqName;
 
-    private KotlinClassFileHeader(int version, @Nullable String[] annotationData, @Nullable HeaderType type, @Nullable FqName fqName) {
+    private KotlinClassFileHeader(int version, @Nullable String[] annotationData, @NotNull HeaderType type, @NotNull FqName fqName) {
         this.version = version;
         this.annotationData = annotationData;
         this.type = type;
@@ -89,15 +93,17 @@ public final class KotlinClassFileHeader {
     }
 
     @Nullable
-    public HeaderType getType() {
-        return type;
+    public String[] getAnnotationData() {
+        if (isCompatibleKotlinCompiledFile() && annotationData == null) {
+            LOG.error("Kotlin annotation " + type + " is incorrect for class: " + fqName);
+            return null;
+        }
+        return annotationData;
     }
 
-    /**
-     * @return true if this is a header for compiled Kotlin file with correct abi version which can be processed by compiler or the IDE
-     */
-    public boolean isCompatibleKotlinCompiledFile() {
-        return type != null && type.isValidAnnotation() && isAbiVersionCompatible(version);
+    @NotNull
+    public HeaderType getType() {
+        return type;
     }
 
     /**
@@ -105,16 +111,14 @@ public final class KotlinClassFileHeader {
      */
     @NotNull
     public FqName getFqName() {
-        assert fqName != null;
         return fqName;
     }
 
-    @Nullable
-    public String[] getAnnotationData() {
-        if (annotationData == null && type != null) {
-            LOG.error("Data for annotations " + type.correspondingAnnotation + " was not read.");
-        }
-        return annotationData;
+    /**
+     * @return true if this is a header for compiled Kotlin file with correct abi version which can be processed by compiler or the IDE
+     */
+    public boolean isCompatibleKotlinCompiledFile() {
+        return type.isValidAnnotation() && isAbiVersionCompatible(version);
     }
 
     private static class ReadDataFromAnnotationVisitor extends ClassVisitor {
diff --git a/idea/src/org/jetbrains/jet/plugin/caches/JetFromJavaDescriptorHelper.java b/idea/src/org/jetbrains/jet/plugin/caches/JetFromJavaDescriptorHelper.java
index dbfc745877e..2fae17dd058 100644
--- a/idea/src/org/jetbrains/jet/plugin/caches/JetFromJavaDescriptorHelper.java
+++ b/idea/src/org/jetbrains/jet/plugin/caches/JetFromJavaDescriptorHelper.java
@@ -102,17 +102,31 @@ public class JetFromJavaDescriptorHelper {
     @Nullable
     private static ClassData getClassData(@NotNull PsiClass psiClass) {
         VirtualFile virtualFile = getVirtualFileForPsiClass(psiClass);
-        if (virtualFile == null) return null;
-        String[] data = KotlinClassFileHeader.readKotlinHeaderFromClassFile(virtualFile).getAnnotationData();
-        return data == null ? null : JavaProtoBufUtil.readClassDataFrom(data);
+        if (virtualFile != null) {
+            KotlinClassFileHeader header = KotlinClassFileHeader.readKotlinHeaderFromClassFile(virtualFile);
+            if (header != null) {
+                String[] data = header.getAnnotationData();
+                if (data != null) {
+                    return JavaProtoBufUtil.readClassDataFrom(data);
+                }
+            }
+        }
+        return null;
     }
 
     @Nullable
     private static PackageData getPackageData(@NotNull PsiClass psiClass) {
         VirtualFile virtualFile = getVirtualFileForPsiClass(psiClass);
-        if (virtualFile == null) return null;
-        String[] data = KotlinClassFileHeader.readKotlinHeaderFromClassFile(virtualFile).getAnnotationData();
-        return data == null ? null : JavaProtoBufUtil.readPackageDataFrom(data);
+        if (virtualFile != null) {
+            KotlinClassFileHeader header = KotlinClassFileHeader.readKotlinHeaderFromClassFile(virtualFile);
+            if (header != null) {
+                String[] data = header.getAnnotationData();
+                if (data != null) {
+                    return JavaProtoBufUtil.readPackageDataFrom(data);
+                }
+            }
+        }
+        return null;
     }
 
     //TODO: common utility
diff --git a/idea/src/org/jetbrains/jet/plugin/libraries/DecompiledDataFactory.java b/idea/src/org/jetbrains/jet/plugin/libraries/DecompiledDataFactory.java
index f414aa3e2c5..5b4ab264fb0 100644
--- a/idea/src/org/jetbrains/jet/plugin/libraries/DecompiledDataFactory.java
+++ b/idea/src/org/jetbrains/jet/plugin/libraries/DecompiledDataFactory.java
@@ -60,7 +60,10 @@ public final class DecompiledDataFactory {
         InjectorForJavaDescriptorResolver injector =
                 new InjectorForJavaDescriptorResolver(project, new BindingTraceContext());
         this.javaDescriptorResolver = injector.getJavaDescriptorResolver();
-        this.kotlinClassFileHeader = KotlinClassFileHeader.readKotlinHeaderFromClassFile(classFile);
+
+        KotlinClassFileHeader header = KotlinClassFileHeader.readKotlinHeaderFromClassFile(classFile);
+        assert header != null : "Decompiled data factory shouldn't be called on an unsupported file: " + classFile;
+        this.kotlinClassFileHeader = header;
     }
 
     @NotNull
diff --git a/idea/src/org/jetbrains/jet/plugin/libraries/DecompiledUtils.java b/idea/src/org/jetbrains/jet/plugin/libraries/DecompiledUtils.java
index 6ee53e6a665..4867389adb7 100644
--- a/idea/src/org/jetbrains/jet/plugin/libraries/DecompiledUtils.java
+++ b/idea/src/org/jetbrains/jet/plugin/libraries/DecompiledUtils.java
@@ -28,7 +28,8 @@ public final class DecompiledUtils {
             return false;
         }
         //TODO: check index
-        return KotlinClassFileHeader.readKotlinHeaderFromClassFile(file).isCompatibleKotlinCompiledFile();
+        KotlinClassFileHeader header = KotlinClassFileHeader.readKotlinHeaderFromClassFile(file);
+        return header != null && header.isCompatibleKotlinCompiledFile();
     }
 
     private DecompiledUtils() {
diff --git a/idea/src/org/jetbrains/jet/plugin/vfilefinder/KotlinClassFileIndex.java b/idea/src/org/jetbrains/jet/plugin/vfilefinder/KotlinClassFileIndex.java
index 3a4a3aebf79..81f95500bfd 100644
--- a/idea/src/org/jetbrains/jet/plugin/vfilefinder/KotlinClassFileIndex.java
+++ b/idea/src/org/jetbrains/jet/plugin/vfilefinder/KotlinClassFileIndex.java
@@ -58,7 +58,7 @@ public final class KotlinClassFileIndex extends ScalarIndexExtension<FqName> {
         public Map<FqName, Void> map(FileContent inputData) {
             try {
                 KotlinClassFileHeader header = KotlinClassFileHeader.readKotlinHeaderFromClassFile(inputData.getFile());
-                if (header.isCompatibleKotlinCompiledFile()) {
+                if (header != null && header.isCompatibleKotlinCompiledFile()) {
                     return Collections.singletonMap(header.getFqName(), null);
                 }
             }