diff --git a/classpath/sun/misc/Unsafe.java b/classpath/sun/misc/Unsafe.java
index ed00ee24ca..e5fd094c45 100644
--- a/classpath/sun/misc/Unsafe.java
+++ b/classpath/sun/misc/Unsafe.java
@@ -73,6 +73,9 @@ public final class Unsafe {
   public native boolean compareAndSwapInt(Object o, long offset, int old,
                                           int new_);
 
+  public native boolean compareAndSwapLong(Object o, long offset,
+                                                 long old, long new_);
+
   public native boolean compareAndSwapObject(Object o, long offset, Object old,
                                              Object new_);
 
diff --git a/src/builtin.cpp b/src/builtin.cpp
index 63b8a42591..ff29d6e3ce 100644
--- a/src/builtin.cpp
+++ b/src/builtin.cpp
@@ -681,6 +681,29 @@ Avian_sun_misc_Unsafe_compareAndSwapInt
     (&fieldAtOffset<uint32_t>(target, offset), expect, update);
 }
 
+extern "C" AVIAN_EXPORT int64_t JNICALL
+Avian_sun_misc_Unsafe_compareAndSwapLong
+(Thread* t UNUSED, object, uintptr_t* arguments)
+{
+  object target = reinterpret_cast<object>(arguments[1]);
+  int64_t offset; memcpy(&offset, arguments + 2, 8);
+  uint64_t expect; memcpy(&expect, arguments + 4, 8);
+  uint64_t update; memcpy(&update, arguments + 6, 8);
+
+#ifdef AVIAN_HAS_CAS64
+  return atomicCompareAndSwap64
+    (&fieldAtOffset<uint64_t>(target, offset), expect, update);
+#else
+  ACQUIRE_FIELD_FOR_WRITE(t, local::fieldForOffset(t, target, offset));
+  if (fieldAtOffset<uint64_t>(target, offset) == expect) {
+    fieldAtOffset<uint64_t>(target, offset) = update;
+    return true;
+  } else {
+    return false;
+  }
+#endif
+}
+
 extern "C" AVIAN_EXPORT void JNICALL
 Avian_sun_misc_Unsafe_unpark
 (Thread* t, object, uintptr_t* arguments)
diff --git a/src/classpath-openjdk.cpp b/src/classpath-openjdk.cpp
index 0dfdae73c5..a49bd43db2 100644
--- a/src/classpath-openjdk.cpp
+++ b/src/classpath-openjdk.cpp
@@ -2898,29 +2898,6 @@ Avian_sun_misc_Unsafe_putOrderedObject
   Avian_sun_misc_Unsafe_putObjectVolatile(t, method, arguments);
 }
 
-extern "C" AVIAN_EXPORT int64_t JNICALL
-Avian_sun_misc_Unsafe_compareAndSwapLong
-(Thread* t UNUSED, object, uintptr_t* arguments)
-{
-  object target = reinterpret_cast<object>(arguments[1]);
-  int64_t offset; memcpy(&offset, arguments + 2, 8);
-  uint64_t expect; memcpy(&expect, arguments + 4, 8);
-  uint64_t update; memcpy(&update, arguments + 6, 8);
-
-#ifdef AVIAN_HAS_CAS64
-  return atomicCompareAndSwap64
-    (&fieldAtOffset<uint64_t>(target, offset), expect, update);
-#else
-  ACQUIRE_FIELD_FOR_WRITE(t, local::fieldForOffset(t, target, offset));
-  if (fieldAtOffset<uint64_t>(target, offset) == expect) {
-    fieldAtOffset<uint64_t>(target, offset) = update;
-    return true;
-  } else {
-    return false;
-  }
-#endif
-}
-
 extern "C" AVIAN_EXPORT int64_t JNICALL
 Avian_sun_misc_Unsafe_pageSize
 (Thread*, object, uintptr_t*)