diff --git a/velox/exec/tests/ExchangeFuzzer.cpp b/velox/exec/tests/ExchangeFuzzer.cpp
index 98ba567cdb05b..fc2b7e073662d 100644
--- a/velox/exec/tests/ExchangeFuzzer.cpp
+++ b/velox/exec/tests/ExchangeFuzzer.cpp
@@ -408,7 +408,7 @@ int main(int argc, char** argv) {
   folly::Init init{&argc, &argv};
   memory::MemoryManagerOptions options;
   options.useMmapAllocator = true;
-  options.allocatorCapacity = 20UL << 30;
+  options.allocatorCapacity = 8UL << 30;
   options.useMmapArena = true;
   options.mmapArenaCapacityRatio = 1;
   memory::MemoryManager::initialize(options);