document rval

1 files changed, 2 insertions, 1 deletions

diff --git a/src/include/gnunet_common.h b/src/include/gnunet_common.h
index f4f68a95f..3ac186e0b 100644
--- a/src/include/gnunet_common.h
+++ b/src/include/gnunet_common.h
@@ -1081,10 +1081,11 @@ GNUNET_ntoh_double (double d);
  *
  * @param a pointer to a struct which should be tested for the
  *          entire memory being zero'ed out.
+ * @return 0 if a is zero, non-zero otherwise
  */
 #define GNUNET_is_zero(a)           \
   ({                                \
-    static const typeof (*a)_z;    \
+    static const typeof (*a) _z;    \
     memcmp ((a), &_z, sizeof(_z)); \
   })