diff --git a/CMakeLists.txt b/CMakeLists.txt
index 41bc507d8..f4fe4c4f3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -47,7 +47,7 @@ endif()
 # Dealing with MOAB
 if (PULL_INSTALL_MOAB)
   # Ensure MOAB_VERSION
-  if(not defined MOAB_VERSION)
+  if(NOT DEFINED MOAB_VERSION)
     set(MOAB_VERSION "5.5.1")
   endif()
   include(MOAB_PullAndMake)