diff --git a/java/jsinterop/base/BUILD b/java/jsinterop/base/BUILD
index 0b8f193..1815367 100644
--- a/java/jsinterop/base/BUILD
+++ b/java/jsinterop/base/BUILD
@@ -40,6 +40,8 @@ javadoc_library(
 j2cl_library(
     name = "base-j2cl",
     srcs = [":processed_j2cl_srcs"] + glob(["*.js"]),
+    # Tested internally in google3
+    experimental_enable_jspecify_support_do_not_enable_without_jspecify_static_checking_or_you_might_cause_an_outage = True,
     deps = [
         "//third_party:jspecify_annotations-j2cl",
         "@com_google_j2cl//:jsinterop-annotations-j2cl",
diff --git a/java/jsinterop/base/InternalJsUtil.java b/java/jsinterop/base/InternalJsUtil.java
index c3cee27..3cb90b0 100644
--- a/java/jsinterop/base/InternalJsUtil.java
+++ b/java/jsinterop/base/InternalJsUtil.java
@@ -60,7 +60,7 @@ public static native Object delete(Object obj, String key) /*-{
   }-*/;
 
   // J2CL_ONLY @JsMethod(name="setIndexed")
-  public static native void set(Object obj, String key, Object value) /*-{
+  public static native void set(Object obj, String key, @Nullable Object value) /*-{
     obj[key] = value;
   }-*/;
 
@@ -92,38 +92,38 @@ public static native void forEach(Object obj, JsForEachCallbackFn cb) /*-{
   }-*/;
 
   // J2CL_ONLY @JsMethod(name="castToAny")
-  public static native boolean asBoolean(Object obj) /*-{
+  public static native boolean asBoolean(@Nullable Object obj) /*-{
    return obj;
   }-*/;
 
   // J2CL_ONLY @JsMethod(name="castToAny")
-  public static native double asDouble(Object obj) /*-{
+  public static native double asDouble(@Nullable Object obj) /*-{
    return obj;
   }-*/;
 
   // J2CL_ONLY @JsMethod(name="castToAny")
-  public static native int asInt(Object obj) /*-{
+  public static native int asInt(@Nullable Object obj) /*-{
     return obj;
   }-*/;
 
   // J2CL_ONLY @JsMethod(name="castToAny")
-  public static native short asShort(Object obj) /*-{
+  public static native short asShort(@Nullable Object obj) /*-{
     return obj;
   }-*/;
 
   // J2CL_ONLY @JsMethod(name="castToAny")
-  public static native char asChar(Object obj) /*-{
+  public static native char asChar(@Nullable Object obj) /*-{
     return obj;
   }-*/;
 
   // J2CL_ONLY @JsMethod(name="castToAny")
-  public static native byte asByte(Object obj) /*-{
+  public static native byte asByte(@Nullable Object obj) /*-{
     return obj;
   }-*/;
 
   @UnsafeNativeLong
   // J2CL_ONLY @JsMethod(name="castToAny")
-  public static native long asLong(Object obj) /*-{
+  public static native long asLong(@Nullable Object obj) /*-{
     return obj;
   }-*/;
 
diff --git a/java/jsinterop/base/InternalPreconditions.java b/java/jsinterop/base/InternalPreconditions.java
index 16098bf..6cf52fb 100644
--- a/java/jsinterop/base/InternalPreconditions.java
+++ b/java/jsinterop/base/InternalPreconditions.java
@@ -24,8 +24,9 @@
  */
 public final class InternalPreconditions {
 
-  private static final boolean IS_TYPE_CHECKED = getProperty("jsinterop.checks").equals("ENABLED");
-  private static final boolean IS_ASSERTED = getProperty("jre.checkedMode").equals("ENABLED");
+  private static final boolean IS_TYPE_CHECKED = getProperty("jsinterop.checks") == "ENABLED";
+
+  private static final boolean IS_ASSERTED = getProperty("jre.checkedMode") == "ENABLED";
 
   public static void checkType(boolean expression) {
     if (IS_TYPE_CHECKED) {
diff --git a/java/jsinterop/base/Js.java b/java/jsinterop/base/Js.java
index 7c37a4a..9d89909 100644
--- a/java/jsinterop/base/Js.java
+++ b/java/jsinterop/base/Js.java
@@ -64,14 +64,12 @@ public static <T> JsConstructorFn<T> asConstructorFn(Class<T> clazz) {
   }
 
   /** Returns {@code JsPropertyMap} view of provided object. */
-  public static @Nullable JsPropertyMap<@Nullable Object> asPropertyMap(
-      @Nullable Object obj) {
+  public static @Nullable JsPropertyMap<@Nullable Object> asPropertyMap(@Nullable Object obj) {
     return uncheckedCast(obj);
   }
 
   /** Returns {@code JsArrayLike} view of provided array-like object. */
-  public static @Nullable JsArrayLike<@Nullable Object> asArrayLike(
-      @Nullable Object obj) {
+  public static @Nullable JsArrayLike<@Nullable Object> asArrayLike(@Nullable Object obj) {
     // TODO(goktug): switch to custom $isInstance
     checkType(obj == null || InternalJsUtil.hasLength(obj));
     return uncheckedCast(obj);
@@ -139,8 +137,7 @@ public static byte asByte(Object obj) {
    * interface to a final Java class (like String).
    */
   @SuppressWarnings({"TypeParameterUnusedInFormals", "unchecked"})
-  public static <T extends @Nullable Object> T cast(
-      @DoNotAutobox @Nullable Object obj) {
+  public static <T extends @Nullable Object> T cast(@DoNotAutobox @Nullable Object obj) {
     return (T) obj;
   }
 
diff --git a/java/jsinterop/base/JsArrayLike.java b/java/jsinterop/base/JsArrayLike.java
index 29e25a5..4a99485 100644
--- a/java/jsinterop/base/JsArrayLike.java
+++ b/java/jsinterop/base/JsArrayLike.java
@@ -67,7 +67,7 @@ default void delete(int index) {
   @JsOverlay
   default List<T> asList() {
     // Since it is hidden behind Arrays.asList, it is safe to do uncheckedCast.
-    T[] asArray = Js.uncheckedCast(this);
+    T[] asArray = Js.<T[]>uncheckedCast(this);
     return Arrays.asList(asArray);
   }
 }