diff --git a/ext/mbstring/config.m4 b/ext/mbstring/config.m4
index 992f0ae7dfa..d51748e2098 100644
--- a/ext/mbstring/config.m4
+++ b/ext/mbstring/config.m4
@@ -283,7 +283,7 @@ if test "$PHP_MBSTRING" != "no"; then
   dnl libmbfl is required
   PHP_MBSTRING_SETUP_LIBMBFL
   PHP_MBSTRING_EXTENSION
-  PHP_INSTALL_HEADERS([ext/mbstring], [libmbfl libmbfl/mbfl])
+  PHP_INSTALL_HEADERS([ext/mbstring], [libmbfl/ libmbfl/mbfl])
 fi
 
 # vim600: sts=2 sw=2 et