--- old/src/os_cpu/linux_s390/vm/atomic_linux_s390.hpp	2017-08-17 13:30:06.938933001 -0400
+++ new/src/os_cpu/linux_s390/vm/atomic_linux_s390.hpp	2017-08-17 13:30:06.826927262 -0400
@@ -489,7 +489,7 @@
                                                 T cmp_val,
                                                 cmpxchg_memory_order unused) const {
   STATIC_ASSERT(4 == sizeof(T));
-  unsigned long old;
+  T old;
 
   __asm__ __volatile__ (
     "   CS       %[old],%[upd],%[mem]    \n\t" // Try to xchg upd with mem.
@@ -503,7 +503,7 @@
     : "cc"
   );
 
-  return IntegerTypes::cast<T>((uint32_t)old);
+  return old;
 }
 
 template<>