diff --git a/TestStrerrorR.cmake b/TestStrerrorR.cmake
index c07847a..507caff 100644
--- a/TestStrerrorR.cmake
+++ b/TestStrerrorR.cmake
@@ -1,6 +1,10 @@
 function(test_strerror_r OUTPUT_VAR HAVE_GNU_SOURCE)
     if (DEFINED STRERROR_R_TEST_RESULT_CACHE)
-        set(${OUTPUT_VAR} ${STRERROR_R_TEST_RESULT_CACHE} PARENT_SCOPE)
+        if (STRERROR_R_TEST_RESULT_CACHE)
+            set(${OUTPUT_VAR} 1 PARENT_SCOPE)
+        else()
+            unset(${OUTPUT_VAR} PARENT_SCOPE)
+        endif()
         message(STATUS "Check strerror_r is GNU complatable - ${STRERROR_R_TEST_RESULT_CACHE} (Cached)")
     else()
         message(STATUS "Check strerror_r is GNU complatable")