diff --git a/runtime/realm/transfer/channel.h b/runtime/realm/transfer/channel.h
index c5803d3049..88393d6b28 100644
--- a/runtime/realm/transfer/channel.h
+++ b/runtime/realm/transfer/channel.h
@@ -227,7 +227,10 @@ namespace Realm {
     protected:
       AddressList *addrlist;
       bool partial;
-      static const int MAX_DIM = 8;
+      // we need to be one larger than any index space realm supports, since
+      //  we use the contiguous bytes within a field as a "dimension" in some
+      //  cases
+      static const int MAX_DIM = REALM_MAX_DIM + 1;
       int partial_dim;
       size_t pos[MAX_DIM];
     };