diff --git a/src/osgViewer/CMakeLists.txt b/src/osgViewer/CMakeLists.txt
index 93ab9cec9..2fa7cfc95 100644
--- a/src/osgViewer/CMakeLists.txt
+++ b/src/osgViewer/CMakeLists.txt
@@ -80,7 +80,7 @@ IF(${OSG_WINDOWING_SYSTEM} STREQUAL "Win32")
         GraphicsWindowWin32.cpp
         PixelBufferWin32.cpp
     )
-ELSIF(${OSG_WINDOWING_SYSTEM} STREQUAL "Cocoa")
+ELSEIF(${OSG_WINDOWING_SYSTEM} STREQUAL "Cocoa")
     ADD_DEFINITIONS(-DUSE_DARWIN_COCOA_IMPLEMENTATION)
 
     IF(OSG_COMPILE_FRAMEWORKS)