diff --git cpp/src/plasma/dlmalloc.cc cpp/src/plasma/dlmalloc.cc
--- cpp/src/plasma/dlmalloc.cc
+++ cpp/src/plasma/dlmalloc.cc
@@ -76,5 +76,8 @@ int create_buffer(int64_t size) {
-  if (!CreateFileMapping(INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE,
-                         (DWORD)((uint64_t)size >> (CHAR_BIT * sizeof(DWORD))),
-                         (DWORD)(uint64_t)size, NULL)) {
+  HANDLE h = CreateFileMapping(INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE,
+                               (DWORD)((uint64_t)size >> (CHAR_BIT * sizeof(DWORD))),
+                               (DWORD)(uint64_t)size, NULL);
+  if (h) {
+    fd = reinterpret_cast<int>(h);
+  } else {
     fd = -1;
   }
--