diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/FqName.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/FqName.java
index 284d5452996..51ef726c404 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/FqName.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/FqName.java
@@ -18,6 +18,7 @@ package org.jetbrains.jet.lang.resolve;
 
 import com.google.common.collect.Lists;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.List;
 
@@ -54,11 +55,22 @@ public class FqName {
 
 
     private void validateFqName() {
-        if (fqName.getFqName().indexOf('<') >= 0) {
+        if (!isValidAfterUnsafeCheck(fqName.getFqName())) {
             throw new IllegalArgumentException("incorrect fq name: " + fqName);
         }
     }
 
+    private static boolean isValidAfterUnsafeCheck(@NotNull String qualifiedName) {
+        // TODO: There's a valid name with escape char ``
+        return qualifiedName.indexOf('<') < 0;
+    }
+
+    public static boolean isValid(@Nullable String qualifiedName) {
+        return qualifiedName != null &&
+               FqNameUnsafe.isValid(qualifiedName) &&
+               isValidAfterUnsafeCheck(qualifiedName);
+    }
+
     @NotNull
     public String getFqName() {
         return fqName.getFqName();
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/FqNameUnsafe.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/FqNameUnsafe.java
index 4050e202e7f..a7d4d02df5e 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/FqNameUnsafe.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/FqNameUnsafe.java
@@ -18,6 +18,7 @@ package org.jetbrains.jet.lang.resolve;
 
 import com.google.common.collect.Lists;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.List;
 
@@ -59,11 +60,16 @@ public class FqNameUnsafe {
 
 
     private void validateFqName() {
-        if (fqName.indexOf('/') >= 0 || fqName.indexOf('*') >= 0) {
+        if (!isValid(fqName)) {
             throw new IllegalArgumentException("incorrect fq name: " + fqName);
         }
     }
 
+    public static boolean isValid(@Nullable String qualifiedName) {
+        // TODO: There's a valid name with escape char ``
+        return qualifiedName != null && qualifiedName.indexOf('/') < 0 && qualifiedName.indexOf('*') < 0;
+    }
+
     private void compute() {
         int lastDot = fqName.lastIndexOf('.');
         if (lastDot >= 0) {
diff --git a/compiler/jet.as.java.psi/src/org/jetbrains/jet/asJava/JavaElementFinder.java b/compiler/jet.as.java.psi/src/org/jetbrains/jet/asJava/JavaElementFinder.java
index 746867c33e3..437e668f6a5 100644
--- a/compiler/jet.as.java.psi/src/org/jetbrains/jet/asJava/JavaElementFinder.java
+++ b/compiler/jet.as.java.psi/src/org/jetbrains/jet/asJava/JavaElementFinder.java
@@ -83,6 +83,10 @@ public class JavaElementFinder extends PsiElementFinder {
     @NotNull
     @Override
     public PsiClass[] findClasses(@NotNull String qualifiedNameString, @NotNull GlobalSearchScope scope) {
+        if (!FqName.isValid(qualifiedNameString)) {
+            return PsiClass.EMPTY_ARRAY;
+        }
+
         FqName qualifiedName = new FqName(qualifiedNameString);
 
         // Backend searches for java.lang.String. Will fail with SOE if continue
@@ -159,6 +163,10 @@ public class JavaElementFinder extends PsiElementFinder {
 
     @Override
     public PsiPackage findPackage(@NotNull String qualifiedNameString) {
+        if (!FqName.isValid(qualifiedNameString)) {
+            return null;
+        }
+
         FqName fqName = new FqName(qualifiedNameString);
 
         final List<JetFile> psiFiles = collectProjectJetFiles(project, GlobalSearchScope.allScope(project));