diff --git a/arch/x86/gen_mmu_x86.py b/arch/x86/gen_mmu_x86.py
index 93a01f50334..395acc8a1b8 100755
--- a/arch/x86/gen_mmu_x86.py
+++ b/arch/x86/gen_mmu_x86.py
@@ -470,7 +470,7 @@ def read_mmu_list(mmu_list_data):
             sys.exit(2)
 
         if (size & 0xFFF) != 0:
-            print("Memory region %d size %zu is not page-aligned" %
+            print("Memory region %d size %d is not page-aligned" %
                     (region_index, size))
             sys.exit(2)