diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 2683f9bbcc..76810d4acf 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -1902,7 +1902,7 @@ fn (mut c Checker) hash_stmt(mut node ast.HashStmt) {
 		else {
 			if node.kind == 'define' {
 				if !c.is_builtin_mod && !c.file.path.ends_with('.c.v')
-					&& !c.file.path.contains('vlib/') {
+					&& !c.file.path.contains('vlib' + os.path_separator) {
 					c.error("#define can only be used in vlib (V's standard library) and *.c.v files",
 						node.pos)
 				}