1 files changed, 2 insertions, 1 deletions

diff --git a/src/CommandOutput.h b/src/CommandOutput.h
index c9aa053c0..8ae50d221 100644
--- a/src/CommandOutput.h
+++ b/src/CommandOutput.h
@@ -16,7 +16,8 @@ public:
 	virtual ~cCommandOutputCallback() {}  // Force a virtual destructor in subclasses
 
 	/** Syntax sugar function, calls Out() with Printf()-ed parameters; appends a newline" */
-	void Out(const char * a_Fmt, ...) FORMATSTRING(2, 3);
+	void Out(const char * a_Fmt, fmt::ArgList);
+	FMT_VARIADIC(void, Out, const char *)
 
 	/** Called when the command wants to output anything; may be called multiple times */
 	virtual void Out(const AString & a_Text) = 0;