diff --git a/hw/vfio/igd.c b/hw/vfio/igd.c
index 0740a5dd8c..b5303ea565 100644
--- a/hw/vfio/igd.c
+++ b/hw/vfio/igd.c
@@ -133,7 +133,7 @@ static uint64_t igd_gtt_memory_size(int gen, uint16_t gmch)
     } else {
         ggms = (gmch >> IGD_GMCH_GEN8_GGMS_SHIFT) & IGD_GMCH_GEN8_GGMS_MASK;
         if (ggms != 0) {
-            ggms = 1 << ggms;
+            ggms = 1ULL << ggms;
         }
     }