diff --git a/cmake/generateConfigFile.cmake b/cmake/generateConfigFile.cmake
index 9fc4e001..adb58d5e 100644
--- a/cmake/generateConfigFile.cmake
+++ b/cmake/generateConfigFile.cmake
@@ -32,6 +32,7 @@ check_cxx_source_compiles( "
 int main() {
     char buff[100];
     const char* c = strerror_r(0,buff,100);
+    (void)c;  // ignore unuse-variable
     return 0;
 }" EXV_STRERROR_R_CHAR_P )