diff --git a/CMakeLists.txt b/CMakeLists.txt
index c8b1c843e..d414fe1d3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -963,10 +963,11 @@ ELSEIF(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
         # remain unset.
 
         IF (APPLE)
-            SET(OSG_CXX_LANGUAGE_STANDARD "C++11" CACHE STRING "set the c++ language standard (C++98 / C++11) for OSG" )
+            SET(OSG_CXX_LANGUAGE_STANDARD "C++11" CACHE STRING "set the c++ language standard (C++98 / GNU++98 / C++11) for OSG" )
             MARK_AS_ADVANCED(OSG_CXX_LANGUAGE_STANDARD)
             # remove existing flags
             REMOVE_CXX_FLAG(-std=c++98)
+            REMOVE_CXX_FLAG(-std=gnu++98)
             REMOVE_CXX_FLAG(-std=c++11)
             REMOVE_CXX_FLAG(-stdlib=libstdc++)
             REMOVE_CXX_FLAG(-stdlib=libc++)
@@ -976,9 +977,15 @@ ELSEIF(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
                 set(CMAKE_XCODE_ATTRIBUTE_CLANG_CXX_LIBRARY "libstdc++")
                 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++98 -stdlib=libstdc++")
             ELSE()
-                set(CMAKE_XCODE_ATTRIBUTE_CLANG_CXX_LANGUAGE_STANDARD "c++11")
-                set(CMAKE_XCODE_ATTRIBUTE_CLANG_CXX_LIBRARY "libc++")
-                set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -stdlib=libc++")
+                IF(${OSG_CXX_LANGUAGE_STANDARD} STREQUAL "gnu++98" OR ${OSG_CXX_LANGUAGE_STANDARD} STREQUAL "GNU++98")
+                    set(CMAKE_XCODE_ATTRIBUTE_CLANG_CXX_LANGUAGE_STANDARD "gnu++98")
+                    set(CMAKE_XCODE_ATTRIBUTE_CLANG_CXX_LIBRARY "libstdc++")
+                    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=gnu++98 -stdlib=libstdc++")
+                ELSE()
+                    set(CMAKE_XCODE_ATTRIBUTE_CLANG_CXX_LANGUAGE_STANDARD "c++11")
+                    set(CMAKE_XCODE_ATTRIBUTE_CLANG_CXX_LIBRARY "libc++")
+                    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -stdlib=libc++")
+                ENDIF()
             ENDIF()
 
             set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-overloaded-virtual -Wno-conversion")