diff --git a/meta/classes/cmake.bbclass b/meta/classes/cmake.bbclass
index 8e579a7f9e..1e72371e76 100644
--- a/meta/classes/cmake.bbclass
+++ b/meta/classes/cmake.bbclass
@@ -35,7 +35,7 @@ cmake_do_generate_toolchain_file() {
 	cat > ${WORKDIR}/toolchain.cmake <<EOF
 # CMake system name must be something like "Linux".
 # This is important for cross-compiling.
-set( CMAKE_SYSTEM_NAME `echo ${SDK_OS} | sed 's/^./\u&/'` )
+set( CMAKE_SYSTEM_NAME `echo ${TARGET_OS} | sed 's/^./\u&/'` )
 set( CMAKE_SYSTEM_PROCESSOR ${TARGET_ARCH} )
 set( CMAKE_C_COMPILER ${OECMAKE_C_COMPILER} )
 set( CMAKE_CXX_COMPILER ${OECMAKE_CXX_COMPILER} )