diff --git a/sys/x86/iommu/intel_gas.c b/sys/x86/iommu/intel_gas.c
index ffc8b7020664..d4aca10ab886 100644
--- a/sys/x86/iommu/intel_gas.c
+++ b/sys/x86/iommu/intel_gas.c
@@ -198,7 +198,7 @@ dmar_gas_check_free(struct dmar_domain *domain)
 			    l->free_down));
 		} else {
 			v = MAX(entry->free_after, l->free_down);
-			v = MAX(entry->free_down, r->free_down);
+			v = MAX(v, r->free_down);
 			MPASS(entry->free_down == v);
 		}
 	}