diff --git a/repos/ports/include/vmm/printf.h b/repos/ports/include/vmm/printf.h
index f7ec54e9b2..9d92228a15 100644
--- a/repos/ports/include/vmm/printf.h
+++ b/repos/ports/include/vmm/printf.h
@@ -23,7 +23,7 @@ namespace Vmm {
 
 	using namespace Genode;
 
-	void printf(const char *format, ...);
+	void printf(const char *format, ...) __attribute__((format(printf, 1, 2)));
 }