diff --git a/ntoskrnl/io/iomgr/driver.c b/ntoskrnl/io/iomgr/driver.c
index ac3ac0f3815..ff61b784a79 100644
--- a/ntoskrnl/io/iomgr/driver.c
+++ b/ntoskrnl/io/iomgr/driver.c
@@ -939,7 +939,7 @@ IopInitializeBuiltinDriver(IN PLDR_DATA_TABLE_ENTRY BootLdrEntry)
         {
             WCHAR num[11];
             UNICODE_STRING instancePath;
-            RtlStringCchPrintfW(num, sizeof(num), L"%u", i);
+            RtlStringCbPrintfW(num, sizeof(num), L"%u", i);
 
             Status = IopGetRegistryValue(enumServiceHandle, num, &kvInfo);
             if (!NT_SUCCESS(Status))