diff --git a/core/include/db_manager.h b/core/include/db_manager.h
index 1d3bd21..847faba 100644
--- a/core/include/db_manager.h
+++ b/core/include/db_manager.h
@@ -34,7 +34,7 @@
   #include <io.h>
   #define access(pathname, mode) _access(pathname, mode)
 
-#elif __unix__
+#elif defined(__unix__)
   #include <unistd.h>
 
 #else