diff --git a/platform/core-impl/src/com/intellij/openapi/editor/impl/IntervalTreeImpl.java b/platform/core-impl/src/com/intellij/openapi/editor/impl/IntervalTreeImpl.java
index c716b7ea96b8..633d402cafaa 100644
--- a/platform/core-impl/src/com/intellij/openapi/editor/impl/IntervalTreeImpl.java
+++ b/platform/core-impl/src/com/intellij/openapi/editor/impl/IntervalTreeImpl.java
@@ -51,7 +51,7 @@ public abstract class IntervalTreeImpl<T extends MutableInterval> extends RedBla
   protected static class IntervalNode<E extends MutableInterval> extends RedBlackTree.Node<E> implements MutableInterval {
     private volatile int myStart;
     private volatile int myEnd;
-    private static final int ATTACHED_TO_TREE_FLAG = 2; // true if the node is inserted to the tree
+    private static final int ATTACHED_TO_TREE_FLAG = COLOR_FLAG+1; // true if the node is inserted to the tree
     protected final List<Getter<E>> intervals;
     protected int maxEnd; // max of all intervalEnd()s among all children.
     protected int delta;  // delta of startOffset. getStartOffset() = myStartOffset + Sum of deltas up to root
@@ -268,7 +268,7 @@ public abstract class IntervalTreeImpl<T extends MutableInterval> extends RedBla
       return myEnd = end;
     }
 
-    private static final int VALID_FLAG = 1;
+    protected static final int VALID_FLAG = ATTACHED_TO_TREE_FLAG + 1;
     @Override
     public boolean isValid() {
       return isFlagSet(VALID_FLAG);
diff --git a/platform/core-impl/src/com/intellij/openapi/editor/impl/RangeMarkerTree.java b/platform/core-impl/src/com/intellij/openapi/editor/impl/RangeMarkerTree.java
index 3c77399b0073..b0bf56ec0af7 100644
--- a/platform/core-impl/src/com/intellij/openapi/editor/impl/RangeMarkerTree.java
+++ b/platform/core-impl/src/com/intellij/openapi/editor/impl/RangeMarkerTree.java
@@ -151,8 +151,8 @@ public class RangeMarkerTree<T extends RangeMarkerEx> extends IntervalTreeImpl<T
   }
 
   static class RMNode<T extends RangeMarkerEx> extends IntervalTreeImpl.IntervalNode<T> {
-    private static final int EXPAND_TO_LEFT_FLAG = 3;
-    private static final int EXPAND_TO_RIGHT_FLAG = 4;
+    private static final int EXPAND_TO_LEFT_FLAG = VALID_FLAG+1;
+    private static final int EXPAND_TO_RIGHT_FLAG = EXPAND_TO_LEFT_FLAG+1;
 
     public RMNode(@NotNull RangeMarkerTree<T> rangeMarkerTree,
                   @NotNull T key,
diff --git a/platform/core-impl/src/com/intellij/openapi/editor/impl/RedBlackTree.java b/platform/core-impl/src/com/intellij/openapi/editor/impl/RedBlackTree.java
index c5151e32a050..6ff5fb91bd17 100644
--- a/platform/core-impl/src/com/intellij/openapi/editor/impl/RedBlackTree.java
+++ b/platform/core-impl/src/com/intellij/openapi/editor/impl/RedBlackTree.java
@@ -299,7 +299,7 @@ public abstract class RedBlackTree<K> {
     protected Node<K> parent = null;
 
     private volatile byte myFlags;
-    private static final int COLOR_FLAG = 0;
+    protected static final int COLOR_FLAG = 0;
 
     protected boolean isFlagSet(int flag) {
       int state = myFlags >> flag;
@@ -307,6 +307,7 @@ public abstract class RedBlackTree<K> {
     }
 
     protected void setFlag(int flag, boolean value) {
+      assert flag < 8;
       int state = value ? 1 : 0;
       myFlags = (byte)(myFlags & ~(1 << flag) | state << flag);
     }
diff --git a/platform/platform-impl/src/com/intellij/openapi/editor/impl/RangeHighlighterData.java b/platform/platform-impl/src/com/intellij/openapi/editor/impl/RangeHighlighterData.java
index 409bf3769719..a3e2ec1eb716 100644
--- a/platform/platform-impl/src/com/intellij/openapi/editor/impl/RangeHighlighterData.java
+++ b/platform/platform-impl/src/com/intellij/openapi/editor/impl/RangeHighlighterData.java
@@ -71,6 +71,7 @@ abstract class RangeHighlighterData {
   }
 
   private void setFlag(@FlagConstant int flag, boolean value) {
+    assert flag < 8;
     int state = value ? 1 : 0;
     myFlags = (byte)(myFlags & ~(1 << flag) | state << flag);
   }