diff --git a/Foundation/CMakeLists.txt b/Foundation/CMakeLists.txt
index da386c53a..62a1ea44e 100644
--- a/Foundation/CMakeLists.txt
+++ b/Foundation/CMakeLists.txt
@@ -156,7 +156,7 @@ else()
 		elseif("${CMAKE_SYSTEM_NAME}" STREQUAL "FreeBSD")
 		  target_compile_definitions(Foundation PUBLIC POCO_HAVE_FD_POLL)
 		  target_link_libraries(Foundation PUBLIC pthread ${CMAKE_DL_LIBS} rt)
-              elseif("${CMAKE_SYSTEM_NAME}" STREQUAL "AIX")
+		elseif("${CMAKE_SYSTEM_NAME}" STREQUAL "AIX")
 		  target_compile_definitions(Foundation PUBLIC  _XOPEN_SOURCE=500 POCO_HAVE_FD_POLL)
 		  target_link_libraries(Foundation PUBLIC pthread ${CMAKE_DL_LIBS} rt)
 		else()