diff --git a/src/mesh/compression/unishox2.c b/src/mesh/compression/unishox2.c
index 2a8d35350..0700c1b36 100644
--- a/src/mesh/compression/unishox2.c
+++ b/src/mesh/compression/unishox2.c
@@ -25,6 +25,7 @@
  * defined in unishox2.h
  */
 
+#define __STDC_WANT_LIB_EXT1__ 1
 #include <stdlib.h>
 #include <string.h>
 #include <ctype.h>