diff --git a/git-compat-util.h b/git-compat-util.h
index 276a43724d..86c8962966 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -4,10 +4,24 @@
 #define _FILE_OFFSET_BITS 64
 
 #ifndef FLEX_ARRAY
-#if defined(__GNUC__) && (__GNUC__ < 3)
-#define FLEX_ARRAY 0
-#else
-#define FLEX_ARRAY /* empty */
+/*
+ * See if our compiler is known to support flexible array members.
+ */
+#if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)
+# define FLEX_ARRAY /* empty */
+#elif defined(__GNUC__)
+# if (__GNUC__ >= 3)
+#  define FLEX_ARRAY /* empty */
+# else
+#  define FLEX_ARRAY 0 /* older GNU extension */
+# endif
+#endif
+
+/*
+ * Otherwise, default to safer but a bit wasteful traditional style
+ */
+#ifndef FLEX_ARRAY
+# define FLEX_ARRAY 1
 #endif
 #endif