diff --git a/Makefile b/Makefile
index 1dd4fa60..ea2b9eed 100644
--- a/Makefile
+++ b/Makefile
@@ -17,7 +17,8 @@ c_test: c
 
 java: transpile_all src/java
 	@if [ ! -f lib/junit4.jar ]; then mkdir lib/; wget -O lib/junit4.jar http://search.maven.org/remotecontent?filepath=junit/junit/4.10/junit-4.10.jar; fi
-	@javac -cp ./lib/junit4.jar -sourcepath ./src/java/src:./src/java/tests src/java/tests/com/facebook/csslayout/*.java
+	@if [ ! -f lib/jsr305.jar ]; then mkdir lib/; wget -O lib/jsr305.jar http://search.maven.org/remotecontent?filepath=net/sourceforge/findbugs/jsr305/1.3.7/jsr305-1.3.7.jar; fi
+	@javac -cp ./lib/junit4.jar:./lib/jsr305.jar -sourcepath ./src/java/src:./src/java/tests src/java/tests/com/facebook/csslayout/*.java
 
 java_test: java
 	@java -cp ./src/java/src:./src/java/tests:./lib/junit4.jar org.junit.runner.JUnitCore \
diff --git a/src/java/src/com/facebook/csslayout/CSSNode.java b/src/java/src/com/facebook/csslayout/CSSNode.java
index 41db5ce4..f8b37a81 100644
--- a/src/java/src/com/facebook/csslayout/CSSNode.java
+++ b/src/java/src/com/facebook/csslayout/CSSNode.java
@@ -6,8 +6,11 @@
  * LICENSE file in the root directory of this source tree. An additional grant
  * of patent rights can be found in the PATENTS file in the same directory.
  */
+
 package com.facebook.csslayout;
 
+import javax.annotation.Nullable;
+
 import java.util.ArrayList;
 
 /**
@@ -242,7 +245,7 @@ public class CSSNode {
     return FloatUtil.floatsEqual(f1, f2);
   }
 
-  protected <T> boolean valuesEqual(T o1, T o2) {
+  protected <T> boolean valuesEqual(@Nullable T o1, @Nullable T o2) {
     if (o1 == null) {
       return o2 == null;
     }