diff --git a/Modules/Platform/SunOS.cmake b/Modules/Platform/SunOS.cmake
index ab9647674..0d3f183c5 100644
--- a/Modules/Platform/SunOS.cmake
+++ b/Modules/Platform/SunOS.cmake
@@ -27,9 +27,9 @@ IF(CMAKE_SYSTEM MATCHES "SunOS-5*.")
   ELSE(CMAKE_COMPILER_IS_GNUCC)
     SET (CMAKE_C_FLAGS_INIT "")
     SET (CMAKE_C_FLAGS_DEBUG_INIT "-g")
-    SET (CMAKE_C_FLAGS_MINSIZEREL_INIT "-O3 -DNDEBUG")
-    SET (CMAKE_C_FLAGS_RELEASE_INIT "-O2 -DNDEBUG")
-    SET (CMAKE_C_FLAGS_RELWITHDEBINFO_INIT "-O2")
+    SET (CMAKE_C_FLAGS_MINSIZEREL_INIT "-xO3 -DNDEBUG")
+    SET (CMAKE_C_FLAGS_RELEASE_INIT "-xO2 -DNDEBUG")
+    SET (CMAKE_C_FLAGS_RELWITHDEBINFO_INIT "-xO2")
   ENDIF(CMAKE_COMPILER_IS_GNUCC)
   IF(CMAKE_COMPILER_IS_GNUCXX)
     SET(CMAKE_SHARED_LIBRARY_CXX_FLAGS "-fPIC") 
@@ -40,9 +40,9 @@ IF(CMAKE_SYSTEM MATCHES "SunOS-5*.")
   ELSE(CMAKE_COMPILER_IS_GNUCXX)
     SET (CMAKE_CXX_FLAGS_INIT "")
     SET (CMAKE_CXX_FLAGS_DEBUG_INIT "-g")
-    SET (CMAKE_CXX_FLAGS_MINSIZEREL_INIT "-O3 -DNDEBUG")
-    SET (CMAKE_CXX_FLAGS_RELEASE_INIT "-O2 -DNDEBUG")
-    SET (CMAKE_CXX_FLAGS_RELWITHDEBINFO_INIT "-O2")
+    SET (CMAKE_CXX_FLAGS_MINSIZEREL_INIT "-xO3 -DNDEBUG")
+    SET (CMAKE_CXX_FLAGS_RELEASE_INIT "-xO2 -DNDEBUG")
+    SET (CMAKE_CXX_FLAGS_RELWITHDEBINFO_INIT "-xO2")
   ENDIF(CMAKE_COMPILER_IS_GNUCXX)
 ENDIF(CMAKE_SYSTEM MATCHES "SunOS-5*.")