diff --git a/src/crypto/crypto.cpp b/src/crypto/crypto.cpp
index f5f5257..a094595 100644
--- a/src/crypto/crypto.cpp
+++ b/src/crypto/crypto.cpp
@@ -221,7 +221,7 @@ DISABLE_VS_WARNINGS(4200)
 POP_WARNINGS
 
   static inline size_t rs_comm_size(size_t pubs_count) {
-    return sizeof(rs_comm) + pubs_count * sizeof(rs_comm().ab[0]);
+    return sizeof(rs_comm) + pubs_count * sizeof(((rs_comm*)0)->ab[0]);
   }
 
   void crypto_ops::generate_ring_signature(const hash &prefix_hash, const key_image &image,