diff --git a/cmake/DefinePlatformSpecifc.cmake b/cmake/DefinePlatformSpecifc.cmake
index f66454ac9..b29640589 100644
--- a/cmake/DefinePlatformSpecifc.cmake
+++ b/cmake/DefinePlatformSpecifc.cmake
@@ -92,7 +92,12 @@ else (CYGWIN)
 	      add_definitions( -DPOCO_HAVE_FD_POLL)
 	      set(SYSLIBS  m socket)
 	    else (QNX)
-	      add_definitions( -D_XOPEN_SOURCE=500 -DPOCO_HAVE_FD_EPOLL)
+	      add_definitions( -D_XOPEN_SOURCE=500)
+	      if (${CMAKE_SYSTEM} MATCHES "AIX")
+	        add_definitions( -DPOCO_HAVE_FD_POLL)
+	      else()
+	        add_definitions( -DPOCO_HAVE_FD_EPOLL)
+	      endif()
 	      set(SYSLIBS  pthread ${CMAKE_DL_LIBS} rt)
 	    endif (QNX)
 	  endif (APPLE)