diff --git a/compiler/frontend.java/src/org/jetbrains/kotlin/load/java/structure/impl/annotationArgumentsImpl.kt b/compiler/frontend.java/src/org/jetbrains/kotlin/load/java/structure/impl/annotationArgumentsImpl.kt
index e24ad8befb5..99fd986f76a 100644
--- a/compiler/frontend.java/src/org/jetbrains/kotlin/load/java/structure/impl/annotationArgumentsImpl.kt
+++ b/compiler/frontend.java/src/org/jetbrains/kotlin/load/java/structure/impl/annotationArgumentsImpl.kt
@@ -34,10 +34,10 @@ abstract class JavaAnnotationArgumentImpl(
             }
 
             return when (argument) {
-                is PsiReferenceExpression -> JavaEnumValueAnnotationArgumentImpl(argument as PsiReferenceExpression, name)
-                is PsiArrayInitializerMemberValue -> JavaArrayAnnotationArgumentImpl(argument as PsiArrayInitializerMemberValue, name)
-                is PsiAnnotation -> JavaAnnotationAsAnnotationArgumentImpl(argument as PsiAnnotation, name)
-                is PsiClassObjectAccessExpression -> JavaClassObjectAnnotationArgumentImpl(argument as PsiClassObjectAccessExpression, name)
+                is PsiReferenceExpression -> JavaEnumValueAnnotationArgumentImpl(argument, name)
+                is PsiArrayInitializerMemberValue -> JavaArrayAnnotationArgumentImpl(argument, name)
+                is PsiAnnotation -> JavaAnnotationAsAnnotationArgumentImpl(argument, name)
+                is PsiClassObjectAccessExpression -> JavaClassObjectAnnotationArgumentImpl(argument, name)
                 else -> throw UnsupportedOperationException("Unsupported annotation argument type: " + argument)
             }
         }
diff --git a/compiler/frontend.java/src/org/jetbrains/kotlin/load/kotlin/incremental/cache/IncrementalCache.kt b/compiler/frontend.java/src/org/jetbrains/kotlin/load/kotlin/incremental/cache/IncrementalCache.kt
index 7a0e14993ee..39d6b3a2497 100644
--- a/compiler/frontend.java/src/org/jetbrains/kotlin/load/kotlin/incremental/cache/IncrementalCache.kt
+++ b/compiler/frontend.java/src/org/jetbrains/kotlin/load/kotlin/incremental/cache/IncrementalCache.kt
@@ -18,7 +18,7 @@ package org.jetbrains.kotlin.load.kotlin.incremental.cache
 
 import java.io.File
 
-public trait IncrementalCache {
+public interface IncrementalCache {
     public fun getObsoletePackageParts(): Collection<String>
 
     public fun getPackageData(fqName: String): ByteArray?
diff --git a/compiler/frontend.java/src/org/jetbrains/kotlin/load/kotlin/incremental/cache/IncrementalCacheProvider.kt b/compiler/frontend.java/src/org/jetbrains/kotlin/load/kotlin/incremental/cache/IncrementalCacheProvider.kt
index 24d516bfa87..0b5a8bba147 100644
--- a/compiler/frontend.java/src/org/jetbrains/kotlin/load/kotlin/incremental/cache/IncrementalCacheProvider.kt
+++ b/compiler/frontend.java/src/org/jetbrains/kotlin/load/kotlin/incremental/cache/IncrementalCacheProvider.kt
@@ -16,6 +16,6 @@
 
 package org.jetbrains.kotlin.load.kotlin.incremental.cache
 
-public trait IncrementalCacheProvider {
+public interface IncrementalCacheProvider {
     public fun getIncrementalCache(moduleId: String): IncrementalCache
 }
diff --git a/compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/KotlinCliJavaFileManager.kt b/compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/KotlinCliJavaFileManager.kt
index cecce802338..51471843de8 100644
--- a/compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/KotlinCliJavaFileManager.kt
+++ b/compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/KotlinCliJavaFileManager.kt
@@ -21,6 +21,6 @@ import com.intellij.psi.impl.file.impl.JavaFileManager
 import com.intellij.psi.search.GlobalSearchScope
 import org.jetbrains.kotlin.name.ClassId
 
-public trait KotlinCliJavaFileManager : JavaFileManager {
+public interface KotlinCliJavaFileManager : JavaFileManager {
     public fun findClass(classId: ClassId, searchScope: GlobalSearchScope): PsiClass?
 }
\ No newline at end of file
diff --git a/compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/jvmSignature/KotlinToJvmSignatureMapper.kt b/compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/jvmSignature/KotlinToJvmSignatureMapper.kt
index 504b5c66aa9..4151400dfbb 100644
--- a/compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/jvmSignature/KotlinToJvmSignatureMapper.kt
+++ b/compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/jvmSignature/KotlinToJvmSignatureMapper.kt
@@ -18,7 +18,7 @@ package org.jetbrains.kotlin.resolve.jvm.jvmSignature
 
 import org.jetbrains.kotlin.descriptors.FunctionDescriptor
 
-public trait KotlinToJvmSignatureMapper {
+public interface KotlinToJvmSignatureMapper {
     public fun mapToJvmMethodSignature(function: FunctionDescriptor): JvmMethodSignature
 }