diff --git a/CMakeLists.txt b/CMakeLists.txt
index e925614d..fa268a13 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -305,21 +305,6 @@ if(CMAKE_SYSTEM_NAME STREQUAL "OpenBSD")
   list(APPEND uv_sources src/unix/openbsd.c)
 endif()
 
-if(CMAKE_SYSTEM_NAME STREQUAL "OS400")
-  list(APPEND uv_cflags -Wno-attributes)
-  list(APPEND uv_defines
-       _ALL_SOURCE
-       _LINUX_SOURCE_COMPAT
-       _THREAD_SAFE
-       _XOPEN_SOURCE=500)
-  list(APPEND uv_sources
-       src/unix/aix-common.c
-       src/unix/ibmi.c
-       src/unix/posix-poll.c
-       src/unix/no-fsevents.c
-       src/unix/no-proctitle.c)
-endif()
-
 if(CMAKE_SYSTEM_NAME STREQUAL "OS/390")
   list(APPEND uv_defines PATH_MAX=255)
   list(APPEND uv_defines _AE_BIMODAL)