diff --git a/README.md b/README.md
index 8afe261..77504be 100644
--- a/README.md
+++ b/README.md
@@ -110,7 +110,7 @@ Example:
 
 ```C
 static BOOL CALLBACK
-ConsoleLogger(_In_ WINTUN_LOGGER_LEVEL Level, _In_ const WCHAR *LogLine)
+ConsoleLogger(_In_ WINTUN_LOGGER_LEVEL Level, _In_z_ const WCHAR *LogLine)
 {
     const WCHAR *Template;
     switch (Level)
diff --git a/api/rundll32.c b/api/rundll32.c
index 164b305..c3ca92c 100644
--- a/api/rundll32.c
+++ b/api/rundll32.c
@@ -35,7 +35,7 @@ WriteFormatted(_In_ DWORD StdHandle, _In_z_ const WCHAR *Template, ...)
 }
 
 static BOOL CALLBACK
-ConsoleLogger(_In_ WINTUN_LOGGER_LEVEL Level, _In_ const WCHAR *LogLine)
+ConsoleLogger(_In_ WINTUN_LOGGER_LEVEL Level, _In_z_ const WCHAR *LogLine)
 {
     const WCHAR *Template;
     switch (Level)