diff --git a/CMakeLists.txt b/CMakeLists.txt
index 59469f588..567f0fb7b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -52,9 +52,9 @@ ENDIF()
 
 IF(ANDROID)
     SET(OSG_WINDOWING_SYSTEM "None" CACHE STRING "Windowing system type for graphics window creation; options: None.")
-ELSIF(WIN32)
+ELSEIF(WIN32)
     SET(OSG_WINDOWING_SYSTEM "Win32" CACHE STRING "Windowing system type for graphics window creation; options: Win32 or None.")
-ELSIF(APPLE)
+ELSEIF(APPLE)
     # custom option to flag an iOS build
     OPTION(OSG_BUILD_PLATFORM_IPHONE "Enable IPhoneSDK Device support" OFF)