diff --git a/h_malloc.c b/h_malloc.c
index 8d76aad..62522af 100644
--- a/h_malloc.c
+++ b/h_malloc.c
@@ -6,8 +6,12 @@
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
-#if N_ARENA > 1
+
+#if __has_include(<threads.h>)
 #include <threads.h>
+#else
+// glibc < 2.28
+#define thread_local _Thread_local
 #endif
 
 #include <malloc.h>