diff --git a/java/java-frontback-psi-api/src/com/intellij/openapi/roots/LanguageLevelProjectExtension.java b/java/java-frontback-psi-api/src/com/intellij/openapi/roots/LanguageLevelProjectExtension.java
index 3f8d5213a88b..01ba835b7348 100644
--- a/java/java-frontback-psi-api/src/com/intellij/openapi/roots/LanguageLevelProjectExtension.java
+++ b/java/java-frontback-psi-api/src/com/intellij/openapi/roots/LanguageLevelProjectExtension.java
@@ -26,22 +26,17 @@ public abstract class LanguageLevelProjectExtension {
 
   public abstract void setLanguageLevel(@NotNull LanguageLevel languageLevel);
 
-  private Boolean myDefault;
-
   /**
    * Auto-detect language level from project JDK maximum possible level.
    * @return null if the property is not set yet (e.g. after migration).
    */
-  public @Nullable Boolean getDefault() {
-    return myDefault;
-  }
+  public abstract @Nullable Boolean getDefault();
 
-  public void setDefault(@Nullable Boolean value) {
-    myDefault = value;
-  }
+  public abstract void setDefault(@Nullable Boolean value);
 
   public boolean isDefault() {
-    return myDefault != null && myDefault;
+    Boolean currentValue = getDefault();
+    return currentValue != null && currentValue;
   }
 
   public void languageLevelsChanged() {
diff --git a/java/java-impl/src/com/intellij/openapi/roots/impl/LanguageLevelProjectExtensionImpl.java b/java/java-impl/src/com/intellij/openapi/roots/impl/LanguageLevelProjectExtensionImpl.java
index 3df3aa197802..9ddefed239f3 100644
--- a/java/java-impl/src/com/intellij/openapi/roots/impl/LanguageLevelProjectExtensionImpl.java
+++ b/java/java-impl/src/com/intellij/openapi/roots/impl/LanguageLevelProjectExtensionImpl.java
@@ -26,7 +26,8 @@ public final class LanguageLevelProjectExtensionImpl extends LanguageLevelProjec
   private static final String DEFAULT_ATTRIBUTE = "default";
 
   private final Project myProject;
-  private LanguageLevel myLanguageLevel;
+  private @Nullable LanguageLevel myLanguageLevel;
+  private @Nullable Boolean myDefault;
   private LanguageLevel myCurrentLevel;
 
   public LanguageLevelProjectExtensionImpl(final Project project) {
@@ -98,6 +99,16 @@ public final class LanguageLevelProjectExtensionImpl extends LanguageLevelProjec
     }
   }
 
+  @Override
+  public @Nullable Boolean getDefault() {
+    return myDefault;
+  }
+
+  @Override
+  public void setDefault(@Nullable Boolean newDefault) {
+    myDefault = newDefault;
+  }
+
   @Override
   public void languageLevelsChanged() {
     languageLevelsChanged(myProject);
diff --git a/java/java-psi-impl/src/com/intellij/core/CoreLanguageLevelProjectExtension.java b/java/java-psi-impl/src/com/intellij/core/CoreLanguageLevelProjectExtension.java
index d632d4f84f37..810f124d587b 100644
--- a/java/java-psi-impl/src/com/intellij/core/CoreLanguageLevelProjectExtension.java
+++ b/java/java-psi-impl/src/com/intellij/core/CoreLanguageLevelProjectExtension.java
@@ -5,10 +5,12 @@ import com.intellij.openapi.roots.LanguageLevelProjectExtension;
 import com.intellij.pom.java.JavaRelease;
 import com.intellij.pom.java.LanguageLevel;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 
 public class CoreLanguageLevelProjectExtension extends LanguageLevelProjectExtension {
   private LanguageLevel myLanguageLevel = JavaRelease.getHighest();
+  private @Nullable Boolean myDefault;
 
   @Override
   public @NotNull LanguageLevel getLanguageLevel() {
@@ -19,4 +21,14 @@ public class CoreLanguageLevelProjectExtension extends LanguageLevelProjectExten
   public void setLanguageLevel(@NotNull LanguageLevel languageLevel) {
     myLanguageLevel = languageLevel;
   }
+
+  @Override
+  public @Nullable Boolean getDefault() {
+    return myDefault;
+  }
+
+  @Override
+  public void setDefault(@Nullable Boolean isDefault) {
+    myDefault = isDefault;
+  }
 }