diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/name/FqName.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/name/FqName.java
index d86ea9056cc..60cd3a837d9 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/name/FqName.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/name/FqName.java
@@ -19,7 +19,6 @@ package org.jetbrains.jet.lang.resolve.name;
 import com.google.common.collect.Lists;
 import com.intellij.openapi.util.text.StringUtil;
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
 
 import java.util.List;
 
@@ -70,12 +69,6 @@ public class FqName extends FqNameBase {
         return qualifiedName.indexOf('<') < 0;
     }
 
-    public static boolean isValid(@Nullable String qualifiedName) {
-        return qualifiedName != null &&
-               FqNameUnsafe.isValid(qualifiedName) &&
-               isValidAfterUnsafeCheck(qualifiedName);
-    }
-
     @Override
     @NotNull
     public String getFqName() {
diff --git a/compiler/frontend/src/org/jetbrains/jet/util/QualifiedNamesUtil.java b/compiler/frontend/src/org/jetbrains/jet/util/QualifiedNamesUtil.java
index 6af6b6446e1..be00e670556 100644
--- a/compiler/frontend/src/org/jetbrains/jet/util/QualifiedNamesUtil.java
+++ b/compiler/frontend/src/org/jetbrains/jet/util/QualifiedNamesUtil.java
@@ -142,4 +142,36 @@ public final class QualifiedNamesUtil {
 
         return isImported(alreadyImported, newImport.fqnPart());
     }
+
+    public static boolean isValidJavaFqName(@Nullable String qualifiedName) {
+        if (qualifiedName == null) return false;
+
+        // Check that it is javaName(\.javaName)* or an empty string
+
+        class State {}
+        State BEGINNING = new State();
+        State MIDDLE = new State();
+        State AFTER_DOT = new State();
+
+        State state = BEGINNING;
+
+        int length = qualifiedName.length();
+        for (int i = 0; i < length; i++) {
+            char c = qualifiedName.charAt(i);
+            if (state == BEGINNING || state == AFTER_DOT) {
+                if (!Character.isJavaIdentifierPart(c)) return false;
+                state = MIDDLE;
+            }
+            else if (state == MIDDLE) {
+                if (c == '.') {
+                    state = AFTER_DOT;
+                }
+                else if (!Character.isJavaIdentifierPart(c)) {
+                    return false;
+                }
+            }
+        }
+
+        return state != AFTER_DOT;
+    }
 }
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 41239f5b720..ec8a6eb06dd 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
@@ -35,6 +35,7 @@ import org.jetbrains.jet.lang.resolve.java.JavaPsiFacadeKotlinHacks;
 import org.jetbrains.jet.lang.resolve.java.PackageClassUtils;
 import org.jetbrains.jet.lang.resolve.name.FqName;
 import org.jetbrains.jet.lang.resolve.name.Name;
+import org.jetbrains.jet.util.QualifiedNamesUtil;
 
 import java.util.Collection;
 import java.util.List;
@@ -77,7 +78,7 @@ public class JavaElementFinder extends PsiElementFinder implements JavaPsiFacade
     @NotNull
     @Override
     public PsiClass[] findClasses(@NotNull String qualifiedNameString, @NotNull GlobalSearchScope scope) {
-        if (!FqName.isValid(qualifiedNameString)) {
+        if (!QualifiedNamesUtil.isValidJavaFqName(qualifiedNameString)) {
             return PsiClass.EMPTY_ARRAY;
         }
 
@@ -162,7 +163,7 @@ public class JavaElementFinder extends PsiElementFinder implements JavaPsiFacade
 
     @Override
     public PsiPackage findPackage(@NotNull String qualifiedNameString) {
-        if (!FqName.isValid(qualifiedNameString)) {
+        if (!QualifiedNamesUtil.isValidJavaFqName(qualifiedNameString)) {
             return null;
         }
 
diff --git a/compiler/tests/org/jetbrains/jet/FqNameTest.java b/compiler/tests/org/jetbrains/jet/FqNameTest.java
index 76475af4f00..9397ca49cee 100644
--- a/compiler/tests/org/jetbrains/jet/FqNameTest.java
+++ b/compiler/tests/org/jetbrains/jet/FqNameTest.java
@@ -20,6 +20,7 @@ import com.google.common.collect.Lists;
 import org.jetbrains.jet.lang.resolve.name.FqName;
 import org.jetbrains.jet.lang.resolve.name.FqNameUnsafe;
 import org.jetbrains.jet.lang.resolve.name.Name;
+import org.jetbrains.jet.util.QualifiedNamesUtil;
 import org.junit.Assert;
 import org.junit.Test;
 
@@ -100,4 +101,25 @@ public class FqNameTest {
         FqNameUnsafe fqName = new FqNameUnsafe("ru.yandex");
         Assert.assertSame(fqName, fqName.toSafe().toUnsafe());
     }
+
+    @Test
+    public void isValidJavaFqName() {
+        Assert.assertTrue(QualifiedNamesUtil.isValidJavaFqName(""));
+        Assert.assertTrue(QualifiedNamesUtil.isValidJavaFqName("a"));
+        Assert.assertTrue(QualifiedNamesUtil.isValidJavaFqName("1"));
+        Assert.assertTrue(QualifiedNamesUtil.isValidJavaFqName("a.a"));
+        Assert.assertTrue(QualifiedNamesUtil.isValidJavaFqName("org.jetbrains"));
+        Assert.assertTrue(QualifiedNamesUtil.isValidJavaFqName("$"));
+        Assert.assertTrue(QualifiedNamesUtil.isValidJavaFqName("org.A$B"));
+
+        Assert.assertFalse(QualifiedNamesUtil.isValidJavaFqName("."));
+        Assert.assertFalse(QualifiedNamesUtil.isValidJavaFqName(".."));
+        Assert.assertFalse(QualifiedNamesUtil.isValidJavaFqName("a."));
+        Assert.assertFalse(QualifiedNamesUtil.isValidJavaFqName(".a"));
+        Assert.assertFalse(QualifiedNamesUtil.isValidJavaFqName("a..b"));
+        Assert.assertFalse(QualifiedNamesUtil.isValidJavaFqName("a.b.."));
+        Assert.assertFalse(QualifiedNamesUtil.isValidJavaFqName("a.b."));
+        Assert.assertFalse(QualifiedNamesUtil.isValidJavaFqName("a.b...)"));
+        Assert.assertFalse(QualifiedNamesUtil.isValidJavaFqName("a.b.<special>"));
+    }
 }
diff --git a/idea/src/org/jetbrains/jet/plugin/completion/weigher/JetExplicitlyImportedWeigher.java b/idea/src/org/jetbrains/jet/plugin/completion/weigher/JetExplicitlyImportedWeigher.java
index 507e3007497..58c6e6a445c 100644
--- a/idea/src/org/jetbrains/jet/plugin/completion/weigher/JetExplicitlyImportedWeigher.java
+++ b/idea/src/org/jetbrains/jet/plugin/completion/weigher/JetExplicitlyImportedWeigher.java
@@ -23,10 +23,10 @@ import org.jetbrains.jet.lang.descriptors.DeclarationDescriptor;
 import org.jetbrains.jet.lang.psi.JetFile;
 import org.jetbrains.jet.lang.resolve.DescriptorUtils;
 import org.jetbrains.jet.lang.resolve.ImportPath;
-import org.jetbrains.jet.lang.resolve.name.FqName;
 import org.jetbrains.jet.lang.resolve.name.FqNameUnsafe;
 import org.jetbrains.jet.plugin.completion.JetLookupObject;
 import org.jetbrains.jet.plugin.quickfix.ImportInsertHelper;
+import org.jetbrains.jet.util.QualifiedNamesUtil;
 
 // class ExplicitlyImportedWeigher extends ProximityWeigher {
 public class JetExplicitlyImportedWeigher extends LookupElementWeigher {
@@ -55,7 +55,7 @@ public class JetExplicitlyImportedWeigher extends LookupElementWeigher {
             if (descriptor != null) {
                 FqNameUnsafe fqName = DescriptorUtils.getFQName(descriptor);
                 // Invalid name can be met for class object descriptor: Test.MyTest.A.<no name provided>.testOther
-                if (FqName.isValid(fqName.toString())) {
+                if (QualifiedNamesUtil.isValidJavaFqName(fqName.toString())) {
                     ImportPath importPath = new ImportPath(fqName.toString());
                     if (ImportInsertHelper.doNeedImport(importPath, file)) {
                         return MyResult.notImported;