diff --git a/rs/java/android/renderscript/RenderScript.java b/rs/java/android/renderscript/RenderScript.java
index 7db331f..eebeaa4 100644
--- a/rs/java/android/renderscript/RenderScript.java
+++ b/rs/java/android/renderscript/RenderScript.java
@@ -1004,6 +1004,14 @@
         }
     }
 
+    void validateObject(BaseObj o) {
+        if (o != null) {
+            if (o.mRS != this) {
+                throw new RSIllegalArgumentException("Attempting to use an object across contexts.");
+            }
+        }
+    }
+
     void validate() {
         if (mContext == 0) {
             throw new RSInvalidStateException("Calling RS with no Context active.");
diff --git a/rs/java/android/renderscript/Script.java b/rs/java/android/renderscript/Script.java
index a1f2287..0e46f94 100644
--- a/rs/java/android/renderscript/Script.java
+++ b/rs/java/android/renderscript/Script.java
@@ -128,6 +128,9 @@
      *
      */
     protected void forEach(int slot, Allocation ain, Allocation aout, FieldPacker v) {
+        mRS.validate();
+        mRS.validateObject(ain);
+        mRS.validateObject(aout);
         if (ain == null && aout == null) {
             throw new RSIllegalArgumentException(
                 "At least one of ain or aout is required to be non-null.");
@@ -152,6 +155,9 @@
      *
      */
     protected void forEach(int slot, Allocation ain, Allocation aout, FieldPacker v, LaunchOptions sc) {
+        mRS.validate();
+        mRS.validateObject(ain);
+        mRS.validateObject(aout);
         if (ain == null && aout == null) {
             throw new RSIllegalArgumentException(
                 "At least one of ain or aout is required to be non-null.");
@@ -187,6 +193,7 @@
      */
     public void bindAllocation(Allocation va, int slot) {
         mRS.validate();
+        mRS.validateObject(va);
         if (va != null) {
             if (mRS.getApplicationContext().getApplicationInfo().targetSdkVersion >= 20) {
                 final Type t = va.mType;
@@ -263,6 +270,8 @@
      *
      */
     public void setVar(int index, BaseObj o) {
+        mRS.validate();
+        mRS.validateObject(o);
         mRS.nScriptSetVarObj(getID(mRS), index, (o == null) ? 0 : o.getID(mRS));
     }