diff --git a/fairmq/plugins/config/Config.cxx b/fairmq/plugins/config/Config.cxx
index bad43b18..99fa3429 100644
--- a/fairmq/plugins/config/Config.cxx
+++ b/fairmq/plugins/config/Config.cxx
@@ -68,7 +68,7 @@ Plugin::ProgOptions ConfigPluginProgramOptions()
         ("init-timeout",        po::value<int           >()->default_value(120),        "Timeout for the initialization in seconds (when expecting dynamic initialization).")
         ("max-run-time",        po::value<uint64_t      >()->default_value(0),          "Maximum runtime for the Running state handler, after which state will change to Ready (in seconds, 0 for no limit).")
         ("print-channels",      po::value<bool          >()->implicit_value(true),      "Print registered channel endpoints in a machine-readable format (<channel name>:<min num subchannels>:<max num subchannels>)")
-        ("shm-segment-size",    po::value<size_t        >()->default_value(2000000000), "Shared memory: size of the shared memory segment (in bytes).")
+        ("shm-segment-size",    po::value<size_t        >()->default_value(2ULL << 30), "Shared memory: size of the shared memory segment (in bytes).")
         ("shm-throw-bad-alloc", po::value<bool          >()->default_value(true),       "Throw a fair::mq::MessageBadAlloc if cannot allocate a message (retry if false).")
         ("shm-monitor",         po::value<bool          >()->default_value(true),       "Shared memory: run monitor daemon.")
         ("ofi-size-hint",       po::value<size_t        >()->default_value(0),          "EXPERIMENTAL: OFI size hint for the allocator.")