diff --git a/fuchsia.cpp b/fuchsia.cpp
index 8ab2b38..9ec0f85 100644
--- a/fuchsia.cpp
+++ b/fuchsia.cpp
@@ -57,8 +57,7 @@
   if (Flags & MAP_NOACCESS)
     return allocateVmar(Size, Data, AllowNoMem);
 
-  const zx_handle_t Vmar = Data ? Data->Vmar : _zx_vmar_root_self();
-  CHECK_NE(Vmar, ZX_HANDLE_INVALID);
+  const zx_handle_t Vmar = (Data && Data->Vmar != ZX_HANDLE_INVALID) ? Data->Vmar : _zx_vmar_root_self();
 
   zx_status_t Status;
   zx_handle_t Vmo;
@@ -126,7 +125,7 @@
     CHECK_EQ(_zx_vmar_destroy(Vmar), ZX_OK);
     CHECK_EQ(_zx_handle_close(Vmar), ZX_OK);
   } else {
-    const zx_handle_t Vmar = Data ? Data->Vmar : _zx_vmar_root_self();
+    const zx_handle_t Vmar = (Data && Data->Vmar != ZX_HANDLE_INVALID) ? Data->Vmar : _zx_vmar_root_self();
     const zx_status_t Status =
         _zx_vmar_unmap(Vmar, reinterpret_cast<uintptr_t>(Addr), Size);
     if (UNLIKELY(Status != ZX_OK))