diff --git a/libraryInterface/Common/src/sun/misc/Unsafe.java b/libraryInterface/Common/src/sun/misc/Unsafe.java
index ff6697af7d..56eb28271e 100644
--- a/libraryInterface/Common/src/sun/misc/Unsafe.java
+++ b/libraryInterface/Common/src/sun/misc/Unsafe.java
@@ -19,6 +19,7 @@
 import org.jikesrvm.classloader.RVMClassLoader;
 import org.jikesrvm.classloader.RVMField;
 import org.jikesrvm.classloader.RVMType;
+import org.jikesrvm.objectmodel.ObjectModel;
 import org.jikesrvm.runtime.Magic;
 import org.jikesrvm.runtime.RuntimeEntrypoints;
 import org.jikesrvm.scheduler.Synchronization;
@@ -62,6 +63,8 @@ public static Unsafe getUnsafe() {
 
   @Inline
   public long allocateMemory(long bytes) {
+    // TODO sysMalloc needs to be changed to Extent because the C
+    // prototype uses size_t
     Address result = SysCall.sysCall.sysMalloc((int)bytes);
     if (result.isZero()) {
       throw new OutOfMemoryError("Unable to satisfy malloc of " + bytes);
@@ -90,7 +93,18 @@ public int pageSize() {
    */
   @Inline
   public void ensureClassInitialized(Class<?> c){
-    // TODO implement
+    RVMType type = JikesRVMSupport.getTypeForClass(c);
+    if (!type.isInitialized()) {
+      if (type.isClassType()) {
+        RuntimeEntrypoints.initializeClassForDynamicLink(type.asClass());
+      } else {
+        // TODO these 3 methods appear a few times in the code base together.
+        // Consider refactoring this
+        type.resolve();
+        type.instantiate();
+        type.initialize();
+      }
+    }
   }
 
   @Inline
@@ -125,8 +139,7 @@ public long objectFieldOffset(Field field) {
 
   @Inline
   public int arrayBaseOffset(Class<?> arrayClass) {
-    // TODO should we get this via ObjectModel?
-    return 0;
+    return ObjectModel.getArrayBaseOffset().toInt();
   }
 
   @Inline
@@ -155,7 +168,7 @@ public void setMemory(long address, long bytes, byte value) {
 
   @Inline
   public void copyMemory(long srcAddress, long destAddress, long bytes) {
-    Memory.memcopy(Address.fromLong(destAddress), Address.fromLong(srcAddress), (int)bytes);
+    Memory.memcopy(Address.fromLong(destAddress), Address.fromLong(srcAddress), Offset.fromLong(bytes).toWord().toExtent());
   }
 
   @Inline
diff --git a/rvm/src/org/jikesrvm/objectmodel/ObjectModel.java b/rvm/src/org/jikesrvm/objectmodel/ObjectModel.java
index a99047c68e..877a04959a 100644
--- a/rvm/src/org/jikesrvm/objectmodel/ObjectModel.java
+++ b/rvm/src/org/jikesrvm/objectmodel/ObjectModel.java
@@ -180,6 +180,16 @@ public static Offset getArrayLengthOffset() {
     return ARRAY_LENGTH_OFFSET;
   }
 
+  /**
+   * NB: this method exists only for documentation purposes.
+   *
+   * @return the offset of the first array element from the array's address
+   *  (in bytes). Always {@code 0} in the current object model.
+   */
+  public static Offset getArrayBaseOffset() {
+    return Offset.zero();
+  }
+
   public static TIB getTIB(ObjectReference ptr) {
     return getTIB(ptr.toObject());
   }