diff --git a/dev/core/super/javaemul/internal/InternalPreconditions.java b/dev/core/super/javaemul/internal/InternalPreconditions.java
index 550b753..d547b34 100644
--- a/dev/core/super/javaemul/internal/InternalPreconditions.java
+++ b/dev/core/super/javaemul/internal/InternalPreconditions.java
@@ -22,11 +22,16 @@
  */
 // Some parts adapted from Guava
 public final class InternalPreconditions {
-  private static final boolean CHECKED_MODE = System.getProperty("superdevmode").equals("on");
-  private static final boolean JSNI_CHECK = System.getProperty("checks.jsni").equals("ENABLED");
-  private static final boolean TYPE_CHECK = System.getProperty("checks.type").equals("ENABLED");
-  private static final boolean API_CHECK = System.getProperty("checks.api").equals("ENABLED");
-  private static final boolean BOUND_CHECK = System.getProperty("checks.bounds").equals("ENABLED");
+  private static final boolean CHECKED_MODE =
+      System.getProperty("superdevmode", "on").equals("on");
+  private static final boolean JSNI_CHECK =
+      System.getProperty("checks.jsni", "ENABLED").equals("ENABLED");
+  private static final boolean TYPE_CHECK =
+      System.getProperty("checks.type", "ENABLED").equals("ENABLED");
+  private static final boolean API_CHECK =
+      System.getProperty("checks.api", "ENABLED").equals("ENABLED");
+  private static final boolean BOUND_CHECK =
+      System.getProperty("checks.bounds", "ENABLED").equals("ENABLED");
 
   public static void checkType(boolean expression) {
     if (TYPE_CHECK) {
diff --git a/user/super/com/google/gwt/emul/java/util/ConcurrentModificationDetector.java b/user/super/com/google/gwt/emul/java/util/ConcurrentModificationDetector.java
index 7458eab..36941e1 100644
--- a/user/super/com/google/gwt/emul/java/util/ConcurrentModificationDetector.java
+++ b/user/super/com/google/gwt/emul/java/util/ConcurrentModificationDetector.java
@@ -23,7 +23,8 @@
  */
 class ConcurrentModificationDetector {
 
-private static final boolean API_CHECK = System.getProperty("checks.api").equals("ENABLED");
+  private static final boolean API_CHECK =
+    System.getProperty("checks.api", "ENABLED").equals("ENABLED");
 
   private static final String MOD_COUNT_PROPERTY = "_gwt_modCount";