diff --git a/ext/dnet/os.h b/ext/dnet/os.h
index cae244781..075f94b2c 100644
--- a/ext/dnet/os.h
+++ b/ext/dnet/os.h
@@ -98,7 +98,8 @@
 
 /* Support for flexible arrays. */
 #undef __flexarr
-#if defined(__GNUC__) && ((__GNUC__ > 2) || (__GNUC__ == 2 && __GNUC_MINOR__ >= 97))
+#if !defined(__clang__) && defined(__GNUC__) && \
+    ((__GNUC__ > 2) || (__GNUC__ == 2 && __GNUC_MINOR__ >= 97))
 /* GCC 2.97 supports C99 flexible array members.  */
 # define __flexarr	[]
 #else