diff --git a/tools/cmake/build.cmake b/tools/cmake/build.cmake
index c9088ba86..9285a53e1 100644
--- a/tools/cmake/build.cmake
+++ b/tools/cmake/build.cmake
@@ -295,7 +295,7 @@ endmacro()
 #
 macro(__build_set_default var default)
     set(_var __${var})
-    if(${_var})
+    if(NOT "${_var}" STREQUAL "")
         idf_build_set_property(${var} "${${_var}}")
     else()
         idf_build_set_property(${var} "${default}")