diff --git a/teavm-classlib/src/main/java/org/teavm/classlib/java/util/TTreeMap.java b/teavm-classlib/src/main/java/org/teavm/classlib/java/util/TTreeMap.java
index 585944995..3b265c1c4 100644
--- a/teavm-classlib/src/main/java/org/teavm/classlib/java/util/TTreeMap.java
+++ b/teavm-classlib/src/main/java/org/teavm/classlib/java/util/TTreeMap.java
@@ -691,7 +691,7 @@ public class TTreeMap<K, V> extends TAbstractMap<K, V> implements TCloneable, TS
         public EntryIterator(TTreeMap<K, V> owner, TreeNode<K, V>[] path, TreeNode<K, V> to, boolean reverse) {
             this.owner = owner;
             modCount = owner.modCount;
-            this.path = TArrays.copyOf(path, owner.root.height);
+            this.path = TArrays.copyOf(path, owner.root == null ? 0 : owner.root.height);
             depth = path.length;
             this.to = to;
             this.reverse = reverse;
diff --git a/teavm-dom/src/main/java/org/teavm/dom/canvas/CanvasGradient.java b/teavm-dom/src/main/java/org/teavm/dom/canvas/CanvasGradient.java
index b374669fd..ba48b01d0 100644
--- a/teavm-dom/src/main/java/org/teavm/dom/canvas/CanvasGradient.java
+++ b/teavm-dom/src/main/java/org/teavm/dom/canvas/CanvasGradient.java
@@ -22,4 +22,14 @@ import org.teavm.jso.JSObject;
  * @author Alexey Andreev
  */
 public interface CanvasGradient extends JSObject {
+    
+    /**
+     * The CanvasGradient.addColorStop() method adds a new stop, defined by an 
+     * offset and a color, to the gradient. If the offset is not between 0 and 1, 
+     * an INDEX_SIZE_ERR is raised, if the color can't be parsed as a CSS color, 
+     * a SYNTAX_ERR is raised.
+     * @param offset Offset between 0 and 1
+     * @param color A CSS parseable color.
+     */
+    void addColorStop(double offset, String color);
 }