diff --git a/CMakeLists.txt b/CMakeLists.txt
index a00f38e001262..3f7dff04eeaf2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -71,7 +71,7 @@ if(NOT $ENV{ROOTSYS} STREQUAL "" AND NOT $ENV{ROOTSYS} STREQUAL "${CMAKE_BINARY_
     endif()
   endfunction()
   strip_path("PATH" "$ENV{ROOTSYS}/bin")
-  if(not WIN32)
+  if(NOT WIN32)
     strip_path("LD_LIBRARY_PATH" "$ENV{ROOTSYS}/lib")
   endif()
   if(APPLE)