Index: CMakeLists.txt
===================================================================
--- CMakeLists.txt
+++ CMakeLists.txt
@@ -233,6 +233,7 @@
 #     The outputs can be compared to gcc.
 #     The outputs match the reference outputs.
 if(ARCH STREQUAL "PowerPC")
+  check_symbol_exists(_LP64 "" PPC_IS_PPC64_ENABLED)
   add_definitions(-ffp-contract=off)
 endif()
 
Index: SingleSource/UnitTests/CMakeLists.txt
===================================================================
--- SingleSource/UnitTests/CMakeLists.txt
+++ SingleSource/UnitTests/CMakeLists.txt
@@ -11,6 +11,9 @@
 endif()
 
 file(GLOB Source RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} *.c *.cpp)
+if(TARGET_OS STREQUAL "AIX" AND ARCH STREQUAL "PowerPC" AND NOT PPC_IS_PPC64_ENABLED) 
+  list(REMOVE_ITEM Source AtomicOps.c)
+endif()
 if(TARGET_OS STREQUAL "Darwin")
   list(REMOVE_ITEM Source 2007-04-25-weak.c)
   if(ARCH STREQUAL "PowerPC")