diff --git a/block/vmdk.c b/block/vmdk.c
index 346bb5cad9..f8c0a4eace 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -401,6 +401,14 @@ static int vmdk_add_extent(BlockDriverState *bs,
         error_report("invalid granularity, image may be corrupt");
         return -EINVAL;
     }
+    if (l1_size > 512 * 1024 * 1024) {
+        /* Although with big capacity and small l1_entry_sectors, we can get a
+         * big l1_size, we don't want unbounded value to allocate the table.
+         * Limit it to 512M, which is 16PB for default cluster and L2 table
+         * size */
+        error_report("L1 size too big");
+        return -EFBIG;
+    }
 
     s->extents = g_realloc(s->extents,
                               (s->num_extents + 1) * sizeof(VmdkExtent));
@@ -598,14 +606,6 @@ static int vmdk_open_vmdk4(BlockDriverState *bs,
     }
     l1_size = (le64_to_cpu(header.capacity) + l1_entry_sectors - 1)
                 / l1_entry_sectors;
-    if (l1_size > 512 * 1024 * 1024) {
-        /* although with big capacity and small l1_entry_sectors, we can get a
-         * big l1_size, we don't want unbounded value to allocate the table.
-         * Limit it to 512M, which is 16PB for default cluster and L2 table
-         * size */
-        error_report("L1 size too big");
-        return -EFBIG;
-    }
     if (le32_to_cpu(header.flags) & VMDK4_FLAG_RGD) {
         l1_backup_offset = le64_to_cpu(header.rgd_offset) << 9;
     }